I used to have extremely bad depression, it comes and goes now but I've been learning how to deal with it and I am infinitely better than I was. First yes, you should just go see someone about it, no big deal, that's why people become psychologists or therapists. One major thing that I find I have to do is really think about things that I enjoy, or used to enjoy, or things that I wish I could do. well instead of wishing I just try to force myself to do them, and I have a blast! But one major thing that deters me or makes me just be like "oh I'll just stay home instead' is Video Games and TV, and when I'm distracting myself with video games or TV, I'm not having fun with EITHER ONE, so what's the point? I try now to only play games with my good friends, and only watch TV with people, otherwise it feeds my depression. ALSO, a really really really big thing in helping me with my depression was my ukulele, I had a uke before, but it was a crappy uke, didn't inspire me to play, when I upgraded though I really pulled out of it. Now I spend most of the time that I would be playing games or watching TV playing my uke instead, looking up music theory on the internet, making music and posting videos of it!