Replying to I think im getting old

so yesterday i was sliding on the floor kinda like single knee disco style. it started because i was chasing my cat, but it was pretty fun so i did it a few more times. (i had been studying for like 4 hours and sort of lost it for a bit haha) today i wake up and my fucking hip is killing me, and i think i pulled a muscle in my leg. wtf, either im in the worst shape of my life or my body is failing already. this shit never happened when i was 16. ya...