1. Read a book - This is one i've been doing a lot the past few months. I used to love reading but for reason stopped, however I recently got back into and have been reading non-stop. I've been thinking of doing a book recommendation post, or something along those lines, let me know what you think!
2. Exercise - Go for a run, or pop down to the gym. Either way, just half an hour of exercise can put you in a better mood and will be of benefit to you too! The first few times is always the worst, but when I get into a routine of exercising I always feel so much better about myself.
3. Do your school/college/uni work - It's always better to get any work you have, done and other with rather than leaving it to the last minute, so why not use your spare time to do it?
4. Run errands - Again, why not sort any errands you have whilst you have some extra time, rather than running around at the last minute to get them done.
5. Meet up with an old friend - A good old catch up with someone you haven't seen in a while is always a good way to spend your time. Why not meet at a coffee shop or go for a bite to eat?