This is one thing that stuck out to me from my own experiences and my friend’s experiences, people can give you some pretty flippant advice on what will fix you. This isn’t to say all advice is bad, but blanket statements and topical cures aren’t going to help the depression sufferer with the deep existential stuff in their core that they are struggling with. Of course exercise can be really helpful for some people, but so is talk therapy, obliging a heartfelt rant without judgement, medicine, occupying yourself with a hobby and etc…In the end if you want to help just be trustworthy and be there for them without judgement, this is the most important thing you can do in my humble opinion.