We joined the YMCA last week. We've been meaning to do something like this for a few years--at least in the winter months--but weren't sure if anything was affordable. But I need to get some exercise in the winter and my main forms are through bicycling and swimming. Both of which aren't very convenient in Minnesota in the winter.
So after school most days I take the kids and we go to the Y for 30 minutes or an hour. We usually just swim. I haven't been able to do laps much, but I take the boys to the deep end and I end up treading water for at least 20 minutes, which is still really good exercise. Occasionally they go to the kids' drop off area and I can ride a stationary bike for 20 minutes or swim a few laps alone.
The hard part is finding the balance in life. We still desire to eat supper together as a family, so that ends up being a little later than usual since we're getting home later, which also means that the kids end up going to bed shortly thereafter and we have less time for getting chores done or having time together at home (and with their mom who doesn't get to go to the Y with us during the week).
It's good for us (me) to be getting more active. Especially in these winter months when seasonal affect disorder can raise its ugly head. It just means some adjustment for us.
One of the things I did while being a stay-at-home parent was a bit of writing. It's one of those things I enjoy. After several years of working to put something together, I am now a published author.