I can never finish what i start?

I have a huge problem and i dont know how to solve it. I cannot concentrate or finish what ive started. Doesnt matter what it is. It isn't being lazy. It happens to things i love too. There are shows I love that I haven't finished. I'd watch a season in a week and then leave it for months and maybe never even finish it. Same with books. I read a few pages and as soon as i put the book down i wont pick it up. Also with writing or making youtube videos. I'd write a page or two or make a video but I can't carry on. Why is that? I have no motivation for anything. It really bothers me. Could it be depression related as i have somethig called "reactive depression" although im recovering from it. It also happens with hobbies. Ive given up so many sports and things such as guitar playing,swimming,horseriding,figure skating,jogging etc. Please help me figure this out. I'm only 16 and its really making me tired that things are the way they are.