What would be a good target for someone who wants to get out of the house and be a bit more active than just generically going to the gym, and doesn't want to a

What would be a good target for someone who wants to get out of the house and be a bit more active than just generically going to the gym, and doesn't want to anticipate winding up with "oh no I'm awake" pain later in life? In terms of what the minimum and maximum baselines would be discipline-wise.