If you have been following the same routine for awhile, you may find you are just going through the motions. It's like driving to work and not remembering the drive. Do you do your workout and not remember it? I get that way sometimes. I'm worrying about what to cook for supper or whether I need to change my oil and don't think about my workout. If that's the case with you it's time for a change. If you are not mentally present and concentrating on what you are doing you aren't receiving the most benefit from it. When you find yourself bored with your routine, sign up for a new class, switch your workout times, find a buddy or hire a trainer. Workout time is for you. Concentrate on yourself and let the rest of the world go. Are you on autopilot?