Lift instinctively so you will enjoy lifting. Keep a split but go without a plan. Lift hard but not so hard so you won't find lifting so hellish that you start missing days. Pick a weight used so you can keep a rhythm to your sets. It's better in my opinion for a guy over 55 to keep a pace when lifting and not be concerned with trying to impress other guys in the gym. Sure you can lift those heavy dumbbells for a set or two of low reps but what will work the muscles is minimal rest between sets using moderate weights. Maybe pick one lift for your show off ego lift and concentrate on it for that single. The rest of the exercises just go hard on the reps but not to absolute failure.
Use the treadmill for distances from 2 to 5 miles. Vary it. I personally hate the treadmill because if you are having a bad day that speed is right in front of your face. If I'm on the road I might slow down but I complete what I started. In other words you do what you can for that day when you're on the road as opposed to seeing the speed on the treadmill.
Also try fast walking on an incline. Most treadmills show a quarter mile track in lights on the display. If not it will show .25 on the distance. Try walking 3.8MPH which is a fast walk. Start the first lap on level incline. The next lap go up 1% grade incline. Every lap or .25 go up 1% incline. In a hypothetical workout let's say you're exhausted at 6% incline. Gut it out and reward your self with a final lap at 0% grade. When you lower your grade to 0% it will feel like you're flying. If you can get up to 12% to 15% you should be in good cardio shape. Consult with a doctor so it doesn't kill you.
Another option is intervals on the treadmill. Start off with light running or fast walking. Do something like running 8 x 440 yards (one lap or .25 distance). Rest in between with fast walking for 220 yards in between. If the treadmill has an electronic display of a track this will be easy. Another common interval workout is 6 x 880 (two laps around or .50) This time use an entire lap of fast walking for the rest interval.
So there are three different approaches on the treadmill. Running distance, fast walking on an incline, and interval running. Mix them up during the week.
Stay away from steroids but use Hormone replacement if you absolutely need it.
