How cliche it might sounds, but there is nothing more powerful than to give this advise for your friends who are currently having a hard time: shit happens but life goes on, thus, stay positive and move on.
A person needs a special ability to be able to stay positive in whatever conditions. Rainy day, sunny day, hard times, or good times. I have been told by a wise man, that positivity is a gift -even though you can create it by yourself!
A positive man will be able to handle disappointment, and rises over and over again until he achieved what he wants in Life. He will not let himself drown in sorrow, because he knows if he tries it one more time -harder, he will get it. Or even if he lost his bet again, nothing will stops him because he believes no matter how dark the night, the sun rises once again.
What we can learn from this positive man, is his ability to accept his failure and to stay positive even in the darkest time. It might be hard, but you know what, I once was a very negative and skeptical person (towards many things in Life). I changed my self little by little, and even though I cannot say now I am a very positive person, I am sure I am on my way.
At least, try.