Rucking. Get a back pack with a chest and waist strap, put in weights (increase over time) or buy a cheap weight lifting belt (Velcro fine) and attach a rope and something that drags (I use an old wheel).

Low impact, good for core strength. Zone 2 approved.

If you are wealthy they make specific back packs or I bought a tacti-cool one on Temu for cheap.

Outlive by Peter Attia is pretty good for more ideas on how to lengthen the mobile portion of your life.