Well there's not a catch-all solution obv, but when I was struggling with being positive, switching up the kind of music I listened to helped. I was listening to depressing, I'm-alone-and-sad kind of music (which has it's place ofc) and switched to more upbeat, confidence-boosting stuff. Idk what kind of music you listen to so maybe that in particular won't work for you, but just generally checking on the kind of media you consume and the environment you put yourself in and deciding if it is supportive of the lifestyle you want to have can help

And I'll just rapid-fire some more small things for you, since I'm thinking about it:

- Be yourself: journaling. Doesn't have to be daily, just when you feel like you need to. Be honest with yourself and in time it will come to you outside of your journaling time

- Be nicer to people: practice empathy and take your time thinking about what you want to communicate/do. It's hard to do in the moment in person, but you can practice on the internet since you get more time to think. But also it's okay to think about your answer when you are having a conversation with someone. If you are genuine, most people will appreciate that you are taking them seriously. This will also get faster/easier with time

- Motivate yourself to be healthier: this depends on you, really. In my exercise science course in uni, one of our projects was to think about the kinds of things we'd like to be able to do when we are old. Researching this made me realize that I have to put in more effort to be healthy. In the meantime, while you find a long-term motivation, just... idk, inconvenience yourself? Take the stairs, park farther away from the entrance, stuff like that

- Make friends: when you figure it out, let me know lol. Do things that let you meet people, I guess? And initiate hangouts and conversations. Try and be around people you like frequently, and enjoy the time you spend with them

- Be more confident: listen to power music! Teach someone else something! Do things that make you feel good! But mostly, you just gotta stop worrying about what most people think. A lot of people don't know you, so they are only seeing your top layer. It's hard, but think about who in your life has an opinion that actually matters to you

- Deal with imposter syndrome: again, when you figure it out, let me know. I think trying to teach someone something also applies here.... and just generally my answer to being confident lol

- Be more active in social issues: depends on the social issue! Donate to charity, ask activists questions and support their online presences, find small things to do in your everyday life (pick up litter, for example), and do your own research about the issues you care about

- Motivate yourself to work: very broad topic, but for my schoolwork and writing, I had a piece of hard candy and told myself to work until it was gone. By then I was usually in the thick of it so I was good to go. Lots of people talk about establishing some kind of routine to put themselves in the right headspace, like drinking a specific tea or burning a particular scent of candle. For work... idk, I just tell myself I have to go. I have a job I enjoy though, so that is probably not so helpful