In about ten minutes, I'm going to go downstairs and work out in the home gym we have. The Boy will come with -obviously; where else is he going to go? - and sit in his chair while I work out. Most of the time, he sits patiently for about twenty minutes, then spends the next 20 minutes fussing - I lift a set, lift the baby; put him down, do the next set, etc. It's all good.
Newborns are really quite good with this sort of thing. They sleep A LOT - and can be put to sleep fairly easily - and don't wake up easily at all. The noise of the weights doesn't bother him (much - I occasionally do startle him with a particularly loud sound), neither does my work out accompaniment - sometimes music, usually a tv show or movie.
This is good when I have to have The Boy with me during times like saxophone lessons, chorus rehearsals or band rehearsals - he'll sleep through most, without being bothered by the extremely loud noises.
Today, The Boy spent about ten minutes on Tummy Time in the little exercise mat we have, which he doesn't like - Tummy Time, not the mat. He struggled to turn for a while, then fell asleep on the mat. Good for him... Anyway, off to work out. Wish me luck - today's leg day.