This. But first, I try to come to terms with the situation and accept the disappointment rather than ignore it.
Just broke up with someone? Take a retrospective look at the relationship. See what lead to the demise. accept that it's in the past, learn from that, and begin the heal (ie. gym, work, girls, time).
Just lost your job? Evaluate why that happened. If the circumstances were not preventable, there's nothing to dwell on; you win some you lose some. If the situation was preventable, learn from your mistakes, grind to get another position, and don't let history repeat itself when you land a gig. In the interim, gym, work (to get another job), girls, time.
Just lost someone close to you to death? Take the time to appreciate the time you spent with them, but allow yourself to grieve. We're humans, death affects us all. No sense in keeping that on the inside. And as always, gym, work, girls, time.
It's times like these where people define themselves. Life is one big learning experience. There will be disappointments. Some may rock you to your core. What matters is your resilience when life knocks you down. Get back on your feet, and dust off your crown. You got this fam.
What has helped me through some particularly tough times is the inescapable realization that there are always others in tougher predicaments who would change lives with me in a heartbeat. Appreciate the struggle. You always come out stronger once you make it to the other end.