I travel with my laptop a lot, but much prefer a beefy workstation for all the work I do when I get where I'm going. The weight of the laptop is not a big deal, even my big Lenovo P53 (~30mm thick 15.6" black brick) is only 3 kg.
I do use an Osprey 22L hiking backpack for my daily driver, it's got a waist belt to transfer weight to my hips, a chest strap to keep the shoulder straps together, and internal semi-rigid frame... but that's more for all my other stuff, and for activities I do in the woods far from stuff like 'laptop computers'. Even if it's just in a handheld briefcase, 3 kg is not a lot. That's about as much as a water bottle - which I also have in the backpack, as well as a bunch of miscellaneous stuff that also weighs a few kg.
I herniated a disk a couple years ago due to a waterskiing accident, but I've fully recovered and even while dealing with that injury, walking around airports and so forth with any laptop is not not strenuous.
In hindsight, I wish I'd gone for the big P73, I miss the giant 17" screen of my old 40mm thick, 3.5 kg Dell Precision... but the OLED on the P53 is beautiful. 17" UHD OLED when, Lenovo?