I have been suffering through depression for many years now, and although I know I need professional help I am too afraid to let anyone in my life know about my problems. I've sort of isolated myself off from everyone and my main form of socialization is through the internet. I'd say for the past ~2 years now I would go to classes talking to no one, commute back home and just sit in my room for the rest of the day. The only people I would really say anything to would be my parents a few minutes a day, when ordering food at school, and the rare occasion a classmate asks a question. Otherwise I'm pretty much in my head 24/7. It was especially hard this past summer because without school I would just be sitting in my room literally all day every day for 4 months straight. I do think about suicide quite often (multiple times a day) although I know that I will probably never act on it, it's just an idea that's always in my head.
I have exercised in the past but I usually lose the motivation to continue after a couple weeks.