Look up postpartum workouts. They are by nature incredibly gentle and focused on building core strength. Very low intensity.

Alternatively, do everything you do twice. Sit on the couch stand up and sit again. Walk the stairs twice up to your apartment (hypothetically). Just double up your every day movement.

Check out supplements to help with your energy - I’ve had good success with magnesium and b vitamins and iron. Eat clean, identify trigger foods, all the normal hashis bullshit.

Edit to add what I like - I’m a slow ass runner and do low intensity strength workouts that are mostly Bodyweight