>>76282434 (OP)Rucking has the lowest risk of accidents, and is the most useful, unless you commute to work by bicycle. After 5-6h, your arms start to hurt fom the reduced bloodflow though, and you only really see improvements from fast, long distance rucks. Protip: Don't fall for goruck and other meme companies, but get a framed pack, like a milsurp alice (with green frame - black frame w/ marpat bag ones are from albania and way to flimsy) instead. your spine will thank you.
Swimming is the most comfy, and has the lowest risk of long-term injuries.
Cycling sucks, but can be easily integrated into your daily routine if you can commute by bike.
Personally, I'm rucking and hiking. Sometimes with weights, sometimes with camping gear, sometimes with SHTF gear.