Preparing to get back into the workforce

Ok for the last 6 years being my grandpa care provider and i enjoyed it. I got to spend all this extra time with a man i looked up to growing up and help make his last days as comfortable as I can make it. Well here's the thing i don't think grandpa have much longer in this world. Getting up there in age. Well 6 years of grandma home cooking and sitting on my ass and watching The Price is Right has left my health into a downward spiral kind of. Im still a strong guy but my stamina is low. I know when i need to go get a new job it probably not going to be as laid-back as my current job but at the same time im having a hard time to get back in to shape. I was just wondering if anyone have good advice to get my fat ass back into shape? Just somthing that well help me stand on my feet for that extra hour.