I found that one of the best advice (successfully tested on myself and others) to help during existential crisis is to remember that someday you are going to die, and work from there.
If you knew you were going to die in ten minutes, what will you do ? What will you regret ? What will you wish you had done ?
Also this : https://www.theguardian.com/lifeandstyle/2012/feb/01/top-fiv...