When I was younger, I used to playing tennis at least 3 days in week. It is really great but I think it's way too tough and intense. So, after playing it, I always want to take a shower and crash. Especially, next day when I did it, many people around me said "Why are you being tired?" or "You look like you are out of energy." That's why when I hit my thirties, I quit playing tennis, and I just take a walk or a jog by the river. Just because I stop to play it doesn't mean it's not good.
