The fact that there is always a positive side to life is the one thing that gives me a lot of happiness. This world is not perfect. There are problems. But things like happiness and unhappiness are relative. Realizing this gives you hope.
Lastly, I would address one general admonition to all: that they consider what are the true ends of knowledge, and that they seek it not either for pleasure of the mind, or for contention, or for superiority to others, or for profit, or fame, or power, or any of these inferior things: but for the benefit and use of life; and that they perfect and govern it in charity.