"Maybe you should try a smaller boulder, then." Magnolia certainly isn't going to advise something sensible like "don't strain yourself", mostly because if someone is going around trying to lift boulders then they're past sensible advice.

"Or something less strenuous?" Fine talk from the person who seems to be finding walking properly strenuous, maybe, but he can still give the advice. "Surely there's other things to do around here."