Is tax to be paid or an amount of money should be paid.
Google.
It depends how long you do it because if you were to doing plank, it can be a choice for you to know when to stop.
Answer: Every activity give tension in the legs. If your willing to make your legs kinda sore try doing jumping squat's or any kind of activity is fine. Some even make your legs burn. But it's not the type of activity's you do it's how much time or how many time's you do it.
