I truly believe that one of the greatest gifts in life is feeling confident in yourself. Here are some rambles that really resonate with me on this topic.
Follow up on yourself and do the things
One of the most important things in order to gain confdience is following through on the things you tell yourself you're going to do. This can be setting a boundary and keeping it. It can also be planning to make time to do a run and actually doing that. It's about eliminating cognitive dissonance and being congruent with what's going on inside of you. Keep the promises you make to yourself.

Whenever you have the feeling you can trust yourself to do these things, you can try to do harder things and accept a challenge. Achieving something immediately boosts your confidence.
"Discipline rooted in shame feels like punishment, but discipline rooted in love feels like self-respect. You deserve to have the best from yourself."
What really helps in this is a can do it mindset. Almost everything that someone else yo know is doing is something you can do as well. There's this tendency in people to look up to others and think "oh I would never be able to do that", but you're actually wrong. Of course, you can. Things don't happen to people because they are smarter or more capable. Sure, privilege and the way you were raised helps a lot, but you are able to do things as well. At least try.
I know the capitalistic mindset of "just work hard, and you'll get there" is just wrong. However, I do strongly believe that people shrink themselves by lowering the expectations of their capabilities beforehand. You are capable of doing hard things!
No one is better than you. Not the person with higher grades, or the one with nicer clothes. Everyone is struggling in their own way, and even if they weren't, that doesn't matter. Just do your own thing.
And, if you are trying to do new things and feel like you suck. Try to enjoy this skill gap that you're currently experiencing. When you're a beginner, you get started because you've acquired a certain taste or love for the outcome. However, you're just a beginner and there's a gap between your taste and your skillset. It's going to take some time to get to the good. Don't get intimated and just get going.
PS: You don't have to be good to do things. You never have to be good, even if you've been doing it for a long time.
Self-love might be a bit overrated
- Emphasis on self-love is a very western idea.
- Body neutrality! Your body is just a body. An amazing living breathing system that is astoundingly intelligent in letting you live. But it's just a body babe.
- You are not that important in the grand scheme of things.

Some more rambles
- Find connection. Having solid people around helps.
- Doing hard things, accepting challenges and making them work → leads to more confidence. To problem-solve creatively. To imagine better things for yourself.
- Look in the mirror and tell yourself positive statements.
- Play. Play trains our brain to think differently.

Reference
- Essay All you have is all you need⤴ by Esther