I'm trying to show my Dad how to lift weights without destroying his back.

Hey All,

My Dad is ~50 and is fairly inactive due to a herniated disk in his back about a decade ago. He also has arthritis in his hips which causes general discomfort if he rides a bike. He's been walking and losing weight but wants me to demystify the gym for him so he can break through some weightless hurdles.

My question is I'm terrified of hurting him. Obviously plan to start off slow on the machines, but in general what are some areas where I should focus so I don't hurt him and scare him off. I'm desperate to help him to get back in shape and stay active, so any advice is welcome.

I should specify that I am a fairly proficient lifter, but am young and don't face the same health issues he does.