Started serious training again for races. Wow as I get older startup of this yearly routine is harder. Even if it is a week off or a year it doesn’t matter. There creaks in body, the endoskeleton, the muscles , the tendons, the ligaments. You have to take that 1 thing at a time. Listen to your body. Accelerate when you can, and slow down when you need to.
The basic startup routine for me is 2-4days of running a week, 1-2 days bike . 2-3 days of core. And no swimming unless needed.