Primary cost of labor is your health. Those kind of jobs aren't done by people over 45. The human body degrades during that sort of work.
I know quite a few old ones and I know many many more who struggle with pain every day as they are my age and talk to me about it. ( IT being my 3rd career after welding and meatcutting ) I have many friends who are dropping out of the workforce and finding alternative jobs because they cant do the work.
Painting is hard work but its one of the less body impacting you can do. There are a few roles like that and yes, being active is a good thing.