Where's your leisure time, out of the house? Your exercise time? Your opportunity to volunteer, do something good for the community and gain all sorts of positive feedback, good feelings about yourself and become further established and respected in your local community (if you'd like to)?
My point being that yes he's doing 'good things' for his health and for other people and that is great. He's also doing things that are fantastically beneficial to his self-esteem, mental health and standing within the community. It's not all altruistic.
Everyone needs good physical and mental health, self-esteem and social interaction. You do too.
You don't need an equally worthy hobby. The basic principle is equal time to yourself, to do with what you will. That's a really simple principle, isn't it? Only a dinosaur who thought that childcare and domestic labour was 'women's work' by default could say otherwise. What does he say when you put that point to him?
Unfortunately it sounds very much as though, for one reason and other, you have become the default parent and housekeeper, on duty or on call 24/7 while he has clearly defined 'work' and 'leisure' time. Further, he feels he can make commitments that commit you to defined periods of domestic work, outside working hours, without fully consulting you, as an equal partner
If so you need to have a big chat about his duty as a parent, a husband and an adult who lives in the house and has a duty to contribute time and effort to the day to day and week to week drudgery of its upkeep.
Then, discuss your mental and physical health and your need for a social life in order to remain a functioning human being.
Volunteering is great but frankly, for your family, it is a luxury, coming after 'basic maintenance of social functioning and mental wellbeing' in any hierarchy of need. You both need to be meeting your basic needs before one of you can devote family time to a luxury. It sounds as though you're not in that position.
What to do - decide on a hobby to do weekly. Could just be 'going for a walk ', or meeting a friend, or an evening class, retreating to a quiet sroom and reading a book (I'd go out to do it though), or, anything at all.
Make it a commitment, stick to that commitment and make everyone else work around and give way to it, just as DH would for governors' meetings or running.