To progress on the quest for fitness and health, you are going to spend some time in the Red Zone. It's at the fuzzy limit of your strength and endurance where, if you stay to long enough, you'll fail. You'll slow down, drop the weight, quit the reps, stop in your tracks.
The Red Zone is a high level of fatigue. You know you've made it to the Red Zone because you are very uncomfortable - gasping for breath, muscles burning, joints straining, heart beating fast. You might feel dizzy or nauseous. Your mind warns you to quit or you might hurt yourself or die.
However, if you are able stay there long enough (just short of failure), you will progress. What progress means for you depends on what you're working on. Maybe you want to add a mile to your normal workout run, or lift a heavier weight, or complete a set of sit ups faster. For a long time it has been well understood in training that you need to regularly push into the Red Zone to improve. It's the whole basis for what trainers call periodization (see Periodization Training for Sports by Tudor O. Bompa, PhD and Michael C. Carrera),internal training, and high intensity exercise.
Your body is built to adapt naturally to physical stress. It's the secret to fitness by which you gradually reach a performance goal by pushing hard for a period of time, resting for a period of time, then coming back and pushing even harder. The adaption process occurs over weeks and months. Elite athletes have schedules carefully designed by their coaches to methodically time this cycle to peak for key competitions.
TOJs can use a similar, toned-down version, alternating hard days and easy days. This TOJ spends some time in every workout (usually 6 days a week) in the Red Zone. There, you live in the now. When to leave the Red Zone, you feel a great sense of satisfaction, sometimes even joy. Sometimes you can use the same approach inside a workout. After a warm up, proceed to the hardest exercises for the first half of your session, then ease back for the second half.
When you're in the Red Zone, you are more prone to injury because you start to loose muscular control as you fatigue. The best protection against this is to be aware of your form. If you are nearing a point where you cannot perform the exercise correctly, stop. You've reached your limit for that day.
The best athletes, regardless of sport or age, are able to spend a long time in the Red Zone. If you want to see what the payoff is, watch this video, a display of the most incredible athleticism and strength this TOJ has ever seen. This is a clip of the Great Chinese Circus performing Swan Lake. You will not believe what two of these dancers (truly awesome athletes) are able to do.
Think of them the next time you get ready to enter the Red Zone.