Disappointment is when you compare your life with others. Just live your life and do things that make you happy. This way you will never be disappointed with yourself. If you fail to achieve something, then tell yourself that you can try again, no worries. :-)

Just find someone whose life is worse than yours, then you'll be happy again.

I try to change my life. Maybe, meet with some new friends or find a new hobby.

I'll do to the beach.

Help someone who is more unfortunate, then you'll feel much better.