I've seen some 500 pound land whales doing flatbed...obviously being 'fit's is not a requirement. Myself, I'm 52, 6'1 220# and, while not in the best shape of my life, I'm not morbid. Neither do I have any ailments (asthma, copd, whatever) that preclude me from being able to do flatbed work. It *is* work sometimes. Chains, tarps, sometimes having to lever parts of the load over a fraction of an inch... and it takes TIME to learn to do it right. (I still cant tarp worth a ####) But, it's more rewarding than just driving a dry van or reefer (IMO) and if you haul machinery, little kids think you're a minor deity...LoL
I just turned 58. Been doing skateboards all my trucking life. I’m 5’6” 190 lbs. I have rotor cup in my shoulder issues but that doesn’t stop me. I improvised and execute. I still throw my 5/16 chains over my loads and straps.
I’m a fat ####### that switched to flatbed from dryvan about a year ago. Really it’s not bad. Yeah it can take a toll chaining and tarping in 105 degree heat but just take a break and drink lots of water. Other than that I’m a bit scared of heights and had to climb on all 4s a couple times tarping tall loads, but I’m getting better at it. I like the extra exercise involved.