A good rule of thumb is to only count something as aerobic activity if you engage in it pretty much continuously for at least 10 minutes at a time. For it to be real aerobic activity it needs to engage your large muscles (butt and legs) and raise your heart rate a bit.
As much as it makes me tired, I don't count walking around in a store as activity because I walk a few feet and then stop, walk a few feet and then stop, etc.
Are you continuously moving for 10+ minutes during the sing/dance class? If so, count it as dancing.
With your time crunch, maybe you would benefit from working out with some videos at home during nap time.
Definitely don't beat yourself up, just look for a productive solution!
My program consists of eating well, getting good exercise and loving life as long and hard as possible.
This is it, your only life.
"Argue for your limitations, and sure enough, they're yours."
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