Perform the following movements back to back with little rest between
Jumping Jacks - 60 seconds
Plank - 60 seconds
Squat (hold dumbbell or kettlebell securely, chest level) - 20 reps
Push-Ups - as many as possible!
One-Arm Dumbbell (or Kettlebell) Row - 20 reps each arm
One-Arm Dumbbell (or Kettlebell) Overhead Press - 20 reps each arm
Rest - 2 or 3 minutes, or until your heart rate settles down and you've caught your breath.
Then repeat the circuit once more. Not bad for minimal equipment and 15
minutes. It'll get your attention! Use perfect form on each and regress moves as needed (research or consult a fitness trainer if you're unsure) and shoot for getting three such strength training sessions in a week. You CAN do it.
As always, consult a physician before beginning ANY exercise regimen.