This whole fitness thing, is, of course, a modern luxury--and necessity. In the olden days, people did not have scales to weigh on or jeans to fit into. Of course, they didn't really need them, since they had to walk twenty miles uphill both ways to get drinking water (which is weird because water flows downhill), or if they were rich, to socialize while their servants fetched it. Still, if you were a rich introvert who lived next to the river, you could just loosen the belt on your tunic a little every year and thank God for your blessings, especially that photography hadn't been invented yet.
My fitness follows its own cycle, like this:
1. I notice that my jeans are not so comfy anymore. I realize I have two options: (a) exercise; (b) go shopping. Nothing is more painful than going shopping, so I decide to exercise.
2. I get up early one morning and do my strength-training workout. I am so together! I am strong and disciplined!
3. I spend the next four days moaning and unable to walk down stairs. I consider the possibility that there are things more painful than going shopping. I straggle through another couple of workouts.
4. The workouts become easier. I do reps between cooking a nutritious breakfast for my children and still am ready to start school on time. Everybody hates me, including me. My jeans start to fit better.
5. A major life crisis occurs, usually involving everyone puking simultaneously, or three out of four parental feet being injured. I drop exercising because I need that time to clean up puke. I eat whatever I can scavenge and I don't sleep well at all.
6. It takes several weeks to recover from the crisis, get the laundry put away, and get back on schedule.
At this point, return to step 1.
It's probably just as well, though, because if I kept going for too long, my jeans might be too big and I would have to go shopping anyway. (Of course, sooner or later clothes wear out, but I try to hide that fact from myself.)