Strangely enough, one of the new features of my running program that helps make it work for me is my required days off. On the days that are not my required days off, if I'm tired and having trouble getting up, I think to myself, "Look, I have to take tomorrow off, so I really need to go today," and, surprisingly, that works!
My previous system was to go at least four times a week, but with the implication that more was better, and without specifying which days (except that I could take no more than two days off in a row, but only rarely: preferably only one).
Nice and flexible, yet clear, right?
But in the morning waking-up haze of having to make a new decision each day, it was too much for me. It became far too easy to find excuses not to go, especially as the semester wore on, time pressures intensified, and the days got shorter and colder. If two days elapsed without running, I knew that I'd have to run now a few days in a row to make my four-times-per-week goal, and so the pressure to go every day would increase. But if (when) that pressure became too much for me and I let myself slip to missing more than two days, then I realized that my next time out would be perceptibly harder. Going out would confirm this, which was discouraging, and so before I knew it, I found myself well along the path of giving up entirely.
The feature that is working surprisingly well for me this time is my specifying exactly which days I must run, and exactly which days I must not run. No new decisions to make. The decision is already made. I just comply. And if I'm grumpy about having to go out, I remind myself that I'll be glad I did, and I also remind myself that tomorrow I get to stay in, and there I go. Simple.
It's funny that this is kind of negative when I usually try to find positive motivations, but, hey, it's working for me right now, so I'll accept it!
And I also trust that the positive addiction (that I'm already seeing signs of) will grow as my fitness level increases.
5 years ago