Before exercise comes diet.
As a rule of thumb try not to eat anything that you couldn't get 200 years ago.
Cut out ALL sugar. (not literally, see comment thread) Make sure you get fiber. Make sure you get water. Dehydration manifests in a lot of ways.
Soda? Stop.
Coffee? Stop. No coffee? Consider starting. Be moderate.
Right after diet, of course, comes exercise. It can't hurt to bike 30 minutes a day.
How do you feel when you wake up on a saturday? When do you wake up? How consistent is your bed-time?
Quality of sleep is important. Are there too many lights on in the room? Too loud? Too cold? What kind of clothes do you wear to bed?
Also, while you're at it, it can't hurt to install f.lux: