Why do bosses ask you to do things they know are not possible for you physically? NB: it’s not even part of your job?

[Anonymous]

Things like carrying heavy equipment up and down a hill and hanging up heavy equipment ( for a petite woman ).

[slatyb]

Where are you? In the US? This is likely a violation of OSHA regulations. It may also amount to constructive dismissal. You might call OSHA or your state employment bureau or an employment lawyer. Or you could just look for a better job.

[Changiis07]

Because the person might say no and just do it. They have to put their foot down

[In_Trance]

You should double check your letter of employment on that one.
I'm sure somewhere in there it asks if you're capable of lifting up to a certain amount.