Hmm, interesting responses. I'm turning 48 this year, and am quite active by most standards. Until this year I typically scored 14+ miles of incidental bike riding per day (my younger kid was in elementary school 3.5 miles away, so I rode him to school and then rode home, repeat at 3), but now I'm finding I need to remember to get out and walk in the sun for an hour or so each day, or do equivalent biking around town.
However, I don't find that for me that does enough to preserve strength. So 2-3 times per week I do a 12-minute HIIT workout (
www.12minuteathlete.com), typically 6 exercises that are done as hard as you can for 30 seconds, with 10 seconds rest, repeat X3. I can't always do the workouts, (or I don't have all the equipment), but it's easy to substitute: today I did squat thrusts (with a cinderblock: not much fancy equipment here) rather than wall balls. I also go to a pilates class once/week, and do a pilates mat routine once/week. That leaves me with a few days for less low-key cardio than just walking for an hour: I'm recovering from an injury that prevents running, but I can hike/almost run uphill for 45 min, or bike, or swim, and I ski patrol at a nordic area, so yesterday I spent 2+ hours out skiing on classic gear and another almost 2 hours skate skiing. Plus, as a present to future me I do pull-ups every other day so that I can continue to do pull-ups every other day and be a bad-ass middle-aged mom!
This all sounds like a lot when I type it out, but, really, an hour a day of walking outside (sometimes even with my husband!) is close to the recommended 10,000 steps, and the other stuff takes either 12 minutes + 4 more minutes for pull-ups, or 25 min - 1 hour for pilates. On the more-cardio days, maybe an hour to 1.5? I work from home, so I typically get to choose when to start and stop, and I wind up right back at home/work, where I can work for a while until I'm ready for a shower (if necessary). Realistically, 1 - 1.5 hours of moving a day is pretty small, considering that you're awake for 16...