The following five things are all very easy and quick things you can do to improve your life. They might have a very big impact on your mood and productivity so make sure that you do all of them.
1. Clean your Room
Keep a clean room/environment. Try to keep it clean once you cleaned it up to save future time and energy. Even if you like things messy it's no excuse to let dust gather and to leave uneaten and uneatable food lying around.
2. Open the Windows
Opening the windows is something simple but very effective. If you haven't let fresh air in for more than a day chances are that you're breathing air of bad quality right now. Breathing fresh air can improve your mood and health a lot. Read more here.
3. Get enough Exercise
Exercise is a crucial part of staying healthy. Walking around outside can easily clear your head and inspire new ideas. It also may keep you from becoming fat.
4. Eat well
Eat well. Make very sure that you have all the vitamins, minerals, and calories you need. Eating well can improve about everything happening in you life. It can help you think clearly and can even improve your IQ.
5. Have Fun
Relieve your stress somehow and set aside some time everyday to do what you want.
Have fun =D