Even if you don't have a big DIY project you've been putting off for ages, you should be able to find some maintenance-related activity to fill a few hours. Maybe there's a table you've been thinking of sanding down or a window frame that needs painting. If the weather's good, you could even go out into the garden and mow the lawn or do a little preening. If the worst comes to the worst, you could settle for having a spring clean through your clothes.
There's no reason you should sit around doing nothing when you could be burning off a few extra calories. If you don't have any fitness equipment, like a rowing machine or a set of weights, you can do a few stretching exercises followed by some push-ups and sit-ups. If you have some old exercise or yoga DVDs that you've never watched, turn them on and have a go.
Cooking is an extremely satisfying activity. The ability to rustle up a tasty home cooked meal is a valuable skill that can bring pleasure to you and others. There's also the fact that people who eat more home cooked meals are statistically less likely to overweight than those who survive predominantly on fast food and ready meals. If you've never really tried cooking at home and usually rely on somebody else to prepare your meals, take a look at what you've got in your refrigerator and see what you can put together. if you don't have any cookbooks lying around for inspiration, look for recipes online.
People are so plugged into electronic media these days, that the pleasure of relaxing with a good book is an experience few manage to make time for. If you've got a few hours to kill, turn your computer and smart phone off and sit down with a cup of coffee, or perhaps even a glass of wine, and get lost in a good novel or an interesting non-fiction work.