I had a suggestion all typed out but didn't hit submit. I'm fat and in not that great of shape so it seems a bit wrong for me to hand out workout advice. That said here goes...
If you haven't lifted for 20yrs I'd suggest you start with bodyweight exercises, especially pushup, pullups, squats, situps, and lunges.
Next I would start on barbell work. Do you have access to "free weights"? I'm not a fan of strength machines. It probably would not be a bad idea to get with a trainer/coach to help you with form on the more typical barbell and olympic lifts. Squats, deadlifts, cleans, presses, etc should be the foundation. Mechanics first, Consistency second, and Intensity third. Though I haven't read it, others here of often suggested the Starting Strength books by Mark Rippetoe. He now also has a website: http://startingstrength.com/index.php/site#.VQBKheE9l_A
