I get so lazy. When I should spend five little minutes after a run doing planks and sit ups and bicycles... I don't. Just a minute a day would help keep me away from injuries. Every month, even week there is a new article with this exercise or that exercise to keep this injury or that injury from affecting you.
The last few days I've been on top of doing a few minutes after every run. Well, except for my 20 mile long run, but just recovering is enough after 20 miles at this point for me. I just realized, as I was thinking about this, the general public does not do core workouts! They don't carry around the guilt of not doing two minutes of planks five days a week. I realized, that we have failed. Oh sure there are a variety of "work" movements that use your core, like moving around bags of dirt, simply standing, or not leaning against anything. However, a growing number of people seem to sit in chairs professionally, and your muscles just decay if you don't use them. (Decay is a strong word, weaken is probably a better one.)
I'm not saying you need to go do 100 sit-ups. I would struggle to do 100 sit-ups! But how about 10? Maybe even just five for starters? Make it five crunches, they are a little easier than full sit-ups. You can't do a plank for a minute? I can't sometimes either. But even doing 10 or 20 little seconds is way better than continuing to sit there, and saying you will start tomorrow. You won't even get sweaty in the fraction of a minute it takes to do three pushups.
Do a little core work, trust me, you'll feel better afterward, provided you don't get hurt in the process. Break it into the smallest possible exercise, do six inches for all of a few seconds, when no one is looking. Your body will thank you.