Give up the things that are going to better yourself mentally, not just physically or on other parameters.
1. Don't dwell in the past
Move on. You can't go back and change it, no matter how hard you try to time jump. Just accept it, move on, and try your best to be better.
2. Staying in your comfort zone
Stop doing it! Get out there! Go take a yoga class instead of sitting in the library by yourself. Even if you want to go to the library, sit at a new table with new people.
3. Social media
We spend too much time on our phones. Even if it's 5-10 minutes at a time, it adds up. Friends post negative things on their social media, the news posts what's wrong in the world on their social media, you can even get frustrated when you can't pass a level of a game you're playing. Take a break. Step away from the phone, tablet, laptop, t.v., anything.
4. Stress
It's not always possible to just get rid of your stress, but you should be able to find ways to de-stress and get rid of what makes you stressful. One way, is minimizing your social media time. It's more possible than you think
5. Bad Relationships
Friendships, significant others, acquaintances, get rid of them. If you don't like them, say bye.
It is a-okay to cut people out of your life if it isn't beneficial in any way shape or form.
6. Comparison
This is probably your worst nightmare and you don't even know it.
Whether you're saying they are better, or they would probably be better, it's a comparison. Appearances, or character traits, it's a comparison.
Get rid of it.