Here are some of the best pieces of advice from two of the best sources on the issue of how to live a good life. They are philosophers Epicurus and Marcus Aurelius.

Marcus Aurelius - Wikipedia

Marcus Aurelius on misfortune

Here is the rule to remember in the future, When anything tempts you to be bitter: not, "This is a misfortune" but "To bear this worthily is good fortune."
- Marcus Aurelius

Marcus Aurelius was a Stoic. The Stoic way of thinking was all about changing ones mind to make the best of those bad situations where one really is helpless to change things. However, this does not mean that Stoics would have thought that people should accept all things as they come.
There are many situations in life where one can not change anything with one's own actions and in these situations the Stoic way of thinking can still be a great tool for retaining ones sanity.

Marcus Aurelius on future

Never let the future disturb you. You will meet it, if you have to, with the same weapons of reason which today arm you against the present."
- Marcus Aurelius

The Stoic way was about removing all unnecessary ballast from ones mind. Carrying fear of unknown future things is often the purest and most destructive form of self-mutilation. However, Marcus Aurelius really thinks that one can avoid it if a person just does put her mind into it.

Epicurus - Wikipedia

Epicurus on the roads end

While we are on the road, we must try to make what is before us better than what is past; when we come to the road's end, we feel a smooth contentment."
- Epicurus (Vatican sayings, 48)

Epicurus gives us a way of seeing that as long things still are in the future, there is the possibility of changing them. Even if our lives have taken a certain course up to this point, we can still change the course of our lives and also reach new levels of happiness at the process, if we choose wisely. It's also about not worrying unnecessarily about the future, but giving it a try at least before succumbing to pessimism and cynicism.

Marcus Aurelius on feelings of injury

Reject your sense of injury and the injury itself disappears."
- Marcus Aurelius

There are mental injuries that are so deep that you just cannot make them disappear, but I still claim that the less you dwell in them, the better you will feel in the long run.
A major problem in philosophy is that it all too often deals in absolutes. Ideas are often presented as quite absolute-sounding things, even if in the real world they can be just worthy goals that one can strive for.
However, one can even vastly improve one's life without really getting to the goal itself, but just by trying to go in the general direction of a goal. This quote just makes no sense if it is interpreted erroneously to include physical injuries.
However, this terse sentence makes a sea of sense when it is understood in the right way, as mental wounds really mostly do happen only in the wounded mind itself. The less one does allow words to bite, the less they really will wound you.

Epicurus on pleasure

The magnitude of pleasure reaches its limit in the removal of all pain. When such pleasure is present, so long as it is uninterrupted, there is no pain either of body or of mind or of both together."
Epicurus (Principal Doctrine 3)

This is a Epicurean doctrine that is misunderstood the most. This misunderstanding is done mostly on purpose by Christians who simply want to make Epicureanism look bad. The Epicurean goal is not at all about hedonism or having uninterrupted pleasure. Pleasure is, in fact, defined as removal of pain and not a physical sensation as such.
The ultimate state of bliss is achieved when one is not in pain in any way either mentally or physically. One really does need no physical pleasures as such to achieve that state. The mental pain if course the most difficult thing in the world to avoid.
Again it is not even stated that such a state would be, in fact, achievable in practice. However, it is about the theoretical maximum state of pleasure or in other words lack of all pain.

Epicurus on overindulgence

No pleasure is a bad thing in itself, but the things which produce certain pleasures entail disturbances many times greater than the pleasures themselves."
-Epicurus (Principal Doctrines, 8)

This doctrine is one of those that are forgotten when people try to portray Epicureans as hedonistic and as people who strive only to reach unlimited pleasures. The big difference to Christianity is that nothing is seen as forbidden or sinful just because of some divine revelation, but things are valued on the benefits and disturbances they bring with them only to a person or the society.
One just needs a rational mind that can do such a valuation. In the Epicurean world, a person must him or herself decide when the negative aspects of an activity bringing pleasure are greater that the good. Epicurean way of thought is based on an expectation of self-discipline. This is just unheard of in Christianity, where a person is not supposed the make this kind of valuations him- or herself at all. One must remember also that Epicureans are not talking about the physical pleasures, but mental pleasures are even more important.

I understand that the 'disturbance' mentioned here is anything that puts things off-balance in ones relationships with other people or one's own mind or body. Disturbances are all the things that disturb "ataraxia" which is a state that is characterized by freedom from worry or any other preoccupation. Many Christian writers have described ataraxia as apathy. That claim is as old as Christianity. Early Christians namely invented things like this just to make their rival, Epicureanism, look bad.
However, the whole thing is a complete forgery. Ataraxia has nothing to do with apathy, but it is the ultimate goal as a state of mind. In it a person is at peace with him or herself and the outside world.

A person can be tremendously active and productive while striving for this kind of greater inner strength and peace. It is not said here that it is really possible to attain a perfect peace of mind.
However, it is a process where a person should avoid such things that disturb his relationships with other people and such actions that make attaining peace in oneís own mind impossible.

Epicurus on pleasures

If every pleasure had been capable of accumulation, not only over time but also over the entire body or at least over the principal parts of our nature, then pleasures would never differ from one another."
- Epicurus - (Principal Dotcrines, 9)

This doctrine can be summed even more sparingly in my own favorite saying: "Too much of most good things can be bad". Overusing even the most pleasant things will ultimately take the pleasure away from them.
This is the hard core of Epicureanism; moderation is the way forward in life in all things. It is not about hedonism. On the contrary it is about controlling hedonistic urges, not by denying access to pleasures, but using rational mind to control ones desires.

Marcus Aurelius on being alive

When you arise in the morning, think of what a precious privilege it is to be alive - to breathe, to think, to enjoy, to love."
- Marcus Aurelius

A lazy moment spent on doing nothing else than letting aimless and free flow of thinking arise can be the best investment you can ever make. Endless lazy hours spent mindlessly looking on the hypnotic eye of the television is, however, a different thing altogether.

Epicurus on death

Death is nothing to us; for that which has been dissolved into its elements experiences no sensations, and that which has no sensation is nothing to us."
- Epicurus (Principal Doctrine 2)

Epicurus is in practice saying here that fear of death is quite unnecessary. In death a person just returns to the state he or she was before he or she was born and there is no pain after that. The fear of death in itself is the enemy, not the inevitable death, that is a similar necessary and vital part of life as birth is.
I know that it is so easy to say this, but so difficult to do. However, the easiest way to diminish fear is to stop unnecessarily thinking about things you fear. This is especially true, if your thinking does not really change anything, but only makes you fear a thing you need not fear.

Epicureans think that living a full and the good life is the best antidote for fear of death. Of course, the religions are feeding on this fear of death. They also do their utmost to keep it up. So it comes as no surprise that death is the main decorative motive in all Christian churches and an instrument of killing is its main symbol.
This Epicurean doctrine is not for those left behind after our death. However, it is about how we personally can deal with the idea of our own death. The loss felt by others can also be lessened if they can accept death as a natural and necessary part of life and not, for example, as a divine sanction for our sins.

After death one does really exist as a memory in other people's minds. A person who leaves good memories with his good actions will live for a long time in those memories after he or she is gone and more importantly will also be remembered fondly.

(This piece was completely reworked on 4th of August, 2012)