Shake it up.
Whatever your routine is, do something different. Why?
I have a neighbor who walks down Blinn Hill every day. It is a mile down from his house (plus his long driveway) and, thus, a mile back up. Sounds like a workout, right?
Not if you do it every day.
It was hard at first, I’m sure. But now he is not even breathing heavy when he gets to the top. His body has adjusted to the work of climbing that hill. If he went down the other side, which is not as steep until the last 300 yards, it would work his legs differently. If he did something crazy, like getting on a bike, well, that would really shake his body up.
So try something different. You might find a new love. And your muscles will let you know you shook them up.