I'm trying to find more ways to do just this in terms of exercising. Many of those moments I have may not allow me the opportunity to run for 45 minutes, but surprisingly many allow me to run 1.5-2 miles.
For example, my daughter's softball game was yesterday. It is 1.5 miles away. I ran there. I left 15 minutes before my husband/kids left the house and we met in the parking lot right on queue. I also ran home afterwards...just made sure I left during the last inning...and I met them at the door (good thing we timed that right, otherwise I would have been sitting on the stoop!).
Today, my husband brought the kids to their soccer practice. 2 miles away. I got home a tad early, raced into my running clothes and off I ran to soccer practice. I get there right before they finish, saw the last 10 minutes of practice, and we all drove home together.
Right there, in the span of two days, I was able to run 5 miles more than any other week...and it hardly took anything away from family time! I'm also running 2-3 days a week during lunch with other people consistently now...which gives me another 5 miles a week. Sure, they will never constitute the necessary "long run", but they sure do increase my bone strength and speed my recovery time. Short runs also help me focus on speed. Since I've been doing a lot of these quick runs, I've seen my speed average 9.5 the first mile...never would have thought that would have happened before. Can I keep it up for 2 miles...not really...yet. But, I'm not exhausted, nor am I about to keel over from lack of oxygen, so there truly is an improvement!
Now, I can never rely on these quick jaunts...but when I see them available, I need to jump on them. For example, I don't see another similar opportunity until next Tuesday for my daughter's next softball game, but I can guarantee you that I will try to squeeze it in! And they have a soccer game next Friday, which I may just be able to run home from since it ends at 6pm. Really, I see no acceptable reason not to do this more often. I just need to plan ahead and have everything I need ready for the waiting.
Again, if exercise is important to you, you need to make it important to everyone around you...you need to make the time!