Unfortunately this is not the job for you.
You must be able to lift heavy containers in the galley when it's your turn to be the galley operator. Also doing tea and coffe service is sometimes exhausting on your wrists when you are working in economy. Pouring for hundreds of people etc...
Also in first aid cases,if a passenger is incapacitated you must assist in helping to carry the pax to the nearest open spot and some passengers are really huge.
Opening doors especially on the boeing you must have strong arms.
The physical aspect of the job is very demanding.