Do a simple program like Strong lifts 5x5. Don't overthink it. Just be consistent. You don't even need to worry about "gains" or anything like that. Just follow the program and do what you can do without pushing too hard and screw up your aging body. Start light and slowly work up.

Don't mess around with a ton of cardio type of stuff. You can add a little of that type of stuff as you want, but focus on the free weights.