I had never even heard of rucking as a sport/pastime until the past couple months.
When we went to Europe two years ago, I picked up a 30L travel backpack, knowing that we would be travelling minimalist, flying those cheap European airlnes in between cities.
I really didn't train for carrying the weight. I was doing a lot of running, but that really doesn't translate to carrying a load. So I struggled a bit, particularly when traveling from airport to hotel, etc.
We are going to Spain April 19-30, and this time around, I put a bunch of weight in my pack to simulate 20 lbs of actual stuff. And I've been doing 4-6 mile hikes with a loaded pack.
I then discovered that there are others out there doing this thing called "rucking". I invested in a GoRuck 4.0. For the past couple weeks, I have been using it. It's definitely a workout. I'm always feeling it after a long hike. I started with the 20 lb weight, but I can go up if I need to 40-45 lbs. Not sure if I'm ever going to do it.
Since retiring in December, I have been focusing on functional fitness. Doing HIIT 2-3 times a week. Now, I do a ruck 2-3 times a week on off-days. I'm in the best shape in about a decade.....from the last time I did HIIT really hard about 10 years ago.