Carry heavy items

If this convo happens again, you could say “oh I am so sorry, I won’t be able to carry this, shall we get xxxx or the team to help?” I think sometimes some people needs to be told in their face. Maybe they genuinely didn’t think through or remember that you mentioned before that you cannot lift heavy items. It takes two hands to clap. You can reiterate and put your point across but also give suggestions on who else can help. Perhaps, that would help you manage the situation better.