Sometimes we feel guilty when we use our time to do things for ourselves, but you should never feel guilty about meditating. If you need a few reasons to keep yourself happy, here are a few (which I've found through numerous sources):
Meditation is good for your health. It decreases blood pressure, and may even help with problems such as artery buildup and heart disease.
Meditation is good for your mind. You'll be more aware and better able to concentrate, and life will become less stressful as a result of regular meditation.
Meditation will make you calmer and happier.
You can find more information on this all over the Internet.
I have written some original meditations that you may find useful. Please feel free to share them if you'd like, but try not to steal them and pass them off as your own. After all, what goes around comes around (times three!).
Here are a few links to some great meditation pages: