any Gym exercise suggestions

my story is that while Im about where I should be weight wise ( 6 ft 4 and tipping 14 stone but sometimes get up to near fifteen if i loose discipline re_ diet ) for aged forty four , I have a permanent foot problem however , due to negligence on the part of someone else , I injured my foot nearly four years ago and have chronic pain whereby im never without some discomfort and when i get flare ups , the pain is really really bad , i sometimes go six months without a flair up but when it arrives it can last for a month , as such I cannot lift anything heavy so lifting weights in a Gym is not an option as all weight goes down , I walk on average twenty five miles per week , bar during flair ups , I am able to walk at a fast pace but this is the only exercise I do and i think i need to improve my upper body strength

I was considering using a rowing machine as you are sitting down , any other suggestions to improve upper body strength which absolutely does not involve lifting weights ?

cheers in advance