Well forty is the beginning of old age. Just wait until you wake up all sore from doing something. Then remember you had not done anything the day before to be sore over. LOL.
I woke up yesterday with a sore right leg. It felt like I had pulled a muscle. All I had done the day before was catch my leg in my coveralls as I was putting them on. Now it has been sore for two days. LOL
The fun of getting old. Welcome to the club.