Yes you do, everyone does unless you want to become overweight/almost overweight
Trust me, I had the same "I don't need it" attitude and I ended up hitting 165 pounds by the time I hit 14. Took 2 years to burn it.
I'm 15, almost 16. Eat like a motherloving pig, pizza and hamburgers out of the ass, bottles and bottles of coke and dr pepper. So much.
I'm 62 Kg, I stand on the weight scale every day and it's not going up.
I know I'm going to
have to exercise one day, but that day is far from now.