You have to give yourself goals to work towards, aspirations are what keep us moving forward.
Take up a hobby with a more "practical" purpose, like Martial Arts, which is very time consuming but also fun, you'll be learning how to defend yourself and if you choose, you can compete in tournaments. This or something like this probably wouldn't feel like a waste of time since it improves your overall quality of life.
You could also get a job that will give you a lot of work, so when you get home those things you feel are a waste of time now become activities that let you relax. Video games and TV are leisure activities and if all you do is game, it can actually get old pretty fast.
Some little things mentioned above include donating blood, maybe community service, clean your house, adopt a kitten. The point is you have to do something that benefits your life or the lives of others, so you can justify that at least your doing something useful... or work your arse off so much that those things that feel like a waste of time no longer do.
I don't know your educational level or work status, if you haven't already gone to college, you could do that also.