Third time's the charm

Well, it has happened again. For the third time in eight months, I threw my back up picking up my children and I haven't been able to stand up straight for a couple of days. You would think that I would have learned after the last two times to start working out in the attempt of developing even a smidgen of a strong core instead of my sorry lack of one, but ... no. I should have expected this one since this weekend is a big, big weekend and the other two times have occurred before big events as well. But! Third time is the charm. Giving the boys a preview of the hunched over frail old lady I hope they take care way down the road has gotten very, very old in itself. So! I'm collecting any and all tips on how to fit building a strong core into small moments of the day. I won't be delusional, I'm determined to get stronger, but I know that I'm not up to joining a gym or doing long videos. What should I do? Plank while brushing my teeth? Maybe planking while the boys are playing around me is more feasible.