I used to run a lot, then changed to a combination of running, biking, walking and weight training six days a week for years. About 2 years ago, I got a huge new job and just didn't have time. I am just now feeling like I am getting my head above water in this new position and have most of the right people in place to take some of the burden off me, so it's back to the gym for me.
Once I'm in the habit, I'm pretty faithful to my routine.