Glad you got out there! For me, all the reasons stated above and I posted in the 300 mile/month thread. During the week the only time I know I can ride is at 5:30 in the morning. When the alarm went off this morning, the bed was exerting a tremendous force on me and almost won. But I decided I was not going to fail at 300 miles and actually want to see how far over that I can go.
The other thing is it takes a while for habits to form and in the beginning it is easy to get off track. But once it does become a habit, I find I start feeling like crud, physically, if I go 3 or more of days without some kind of exercise.