Honestly the world is your oyster. You really haven't put much thought into this cos I've come up with all these ideas already:
Go shopping
Go to theme parks
Eat out with friends and family
Trips to the park when the weather is nice
Travel to new places
Visit friends and family
Start a blog or other creative passion - writing, knitting etc
Get involved in public classes/groups - fitness, dance etc
Go to the gym
Play sports
Go to festivals
Volunteering - you don't need to be 16 to do this
And on top of that, you can watch TV/films and play games in your down time.