Good morning Bob @unclebob83 - Our friend John gave you some great resources, and having recently dealt with the same situation with my "best cousin" and a few years ago with my sister, maybe I can add a few ideas?

First, make sure your sister is OK with your idea of pushing him, and will continue the effort once you leave. Both my brother-in-law and my cousin's partner would rather be full-time caregivers than "the bad guy" pushing their loved one. If you do spend weeks getting him moving, only to have your sister let him backslide, you may resent both of them.

If she is not on board with your idea, you can still be of tremendous help to her, if you visit with the idea of providing her with company & respite (maybe she can take a few days to visit a friend or her kids?) and taking care of all the little stuff that falls by the wayside during full-time caregiving. Think neglected chores like defrosting the freezer, deep cleaning, minor repairs. And you will get a first hand look at exactly what is going on - maybe there is more going on like cognitive impairment, prostate issues, etc.

It may also become apparent that BOTH of them need more help or a more supportive living situation. Sometimes when a caregiver is barely getting by themselves, they don' have the energy to do more than just make it through the day. If so, maybe you can help your sister figure out what to do next.

Finally, make sure they both have their paperwork in place - Advanced Directives, Powers of Attorney, Wills, etc, so they are prepared for a health crisis for either of them.

It is great that you are going to help out. If for no other reason than to provide some support.