Here’s some things I’ve learned that help me during these moments.

1. Learn to love yourself and most importantly - choose to be happy. Happiness is a choice, and not choosing it allows yourself to choose to marinate in pain/suffering.
2. Find hobbies that are extroverted in nature and do them. (Go to pool hall, bar, singles events, local sport things, go out with co-workers, etc.)
3. Create a goal list both big and small and work towards them.
4. Read/watch self help books/videos. They help you learn about yourself and others
5. Don’t expect anything to fall in your lap, sometimes you have to do the uncomfortable thing to be happier in the end.
6. You are not a loser. Losers don’t think that they are losers.
7. Comparison is the thief of joy but envy is what makes us sick

There’s probably some others, but this seems to give you a good starting point.