Don't do the same workout over and over. Your body only changes when you force it to, and it's remarkably quick to adapt to new stimuli. If you repeat the same workout every training session even for a month, your body can probably handle it without producing an adaptive response. If you feel like your progress has reached a plateau, that's probably what's happening. The best way to avoid plateaus is by periodizing your training, which simply means arranging it according to discrete phases designed to achieve different, albeit related, goals, including muscle growth, strength and definition. That's also the best way to avoid overtraining.
"The best cardio workout is the jump-rope. It's intense: You'll burn so many calories per minute! Do a basic jump for five minutes, then jump twice as high and turn the rope twice as fast so it passes under your feet twice before you land. This takes timing, patience and power. But you'll get in great shape just by working at it...."