Well it really does depend on a lot of things. How you are, how the baby is, whether there are other children, whether he's pulling his weight and so on, whether he's generally a good husband.
Although exercise is important, it's not going to kill anyone to skip the gym for a while until everyone's adjusted to life with the new baby. Otoh, if the wife is fine and happy to be alone with a sleeping baby then there's no problem is there? But some people painting this idyllic scene of sleeping baby and mum laying on sofa with chocolate happy watching tv isn't always the reality.
What I do find laughable is all these posts saying their dhs needed to 'de-stress'. What utter bollox, the woman is the one whose been through pregnancy and childbirth, then breastfeeding.
I'm struggling to see how a coping mechanism for watching your wife in pain is to disappear for a few hours, leaving her at home in pain.
Surely being on hand at home would be the obvious thing?