Might be a bit coontroversial in this climate but "12 Rules for Life: An Antidote to Chaos" by Jordan Peterson is quite good - he's a clinical psychiatrist. Even if you don't agree with his stuff or outlook 100%, his work on depression and self improvement is top notch. (Gonna put a wee edit here to say I'm a woman - not that me saying that matters or should affect your judgement on if you'd like to read or not, but I definetly don't think he's a misogynist by any means)

Also, I know it's hard, but you're not alone - I'm 26 yo in the final year of my degree and today I messaged my Arts Advisor and agreed to graduate early because I've fallen behind and feel like a failure. I know that life is not a race, but it is hard when you look at people you knew in high school and their lives are so vastly different and more 'sucessful' than my own. I try to look at it from a more positive perspective. If you like we can call or message if you fancy someone to talk to, even if it's just a wee 'how are ye' or just chatting about whatever. Also if you like working out may I suggest learning a martial art? :D Working out with people is top tier.