“Pack a tire on your back and carry it for a while.”
Best way to train: Sand bag carry and/or buddy carry. Finish off your runs by carrying something heavy—like your training partner or your dog. Alternate every 100 yards (unless you’re carrying your dog—then don’t alternate). In the weight room—sandbag fireman carry—80 yards. You’ll develop the core strength and stability to carry whatever they throw your way.