Things started going down hill at 72 for me. Sold the race are thee years ago because I wasn’t consistent on the tree anymore. That didn’t stop me I’ve built three street rods since then. I started a fourth one last month. Almost have the new frame fabrication completed. Finished the engine assembly two days ago. I’m 77 now. The secret is don’t stop, keep doing what you enjoy but at a slower pace. I still spend at least six hours a day in my shop.