Exercize & Productivity

I was extremely productive last week, thanks in part to Google Calendar and--I'm now realizing--exercise. This week I was not as productive, thanks in part to some family crises (not my own), other interruptions, and--I now realize--a lack of exercise.
I didn't do much bike riding this week. I ate decently, but not great; I was on the road a lot. Its been a real struggle to get out of bed this week; not so last week, when I exercised every day. So, last night I forced myself to get on the bike--with a little encouragement from Tammy. When 6:50 rolled around this morning I was ready to take the boys to school, and the next 20 minutes I spent lying in the bed was relaxing and enjoyable (since I was ready to get up). Later today I decided to ride the bike again before I jumped in the shower (I could do that b/c it's my day off). I had lots of energy and felt like being productive again.
So, is there a correlation? I think so. I think I might like this exercise thing for the mental and emotional effects and increased productivity even more than the weightloss.