Heart Health
Tracking numbers that assess your cardiovascular condition will give you a clear picture of your overall fitness. The stronger your heart, the harder you can exercise. And the harder you can exercise, the more calories you'll burn during your workouts. But there's another reason to monitor your heart health. As you become fitter, your body will build more muscle. A pound of muscle burns more calories than a pound of fat, so increasing your muscle mass allows you to burn more calories at rest. You can easily measure all of these numbers with a heart-rate monitor. In some cases, the rate at which the numbers change over time matters more than the actual figures.Resting Heart Rate (RHR)
Once a week, take your pulse for one minute first thing in the morning the day after a rest day. Compare the number weekly. You'll start to see trends (for example, a slightly higher RHR may indicate you're dehydrated). If your resting heart rate gradually decreases over time, it means you're getting fitter.One-Minute Heart Recovery Rate
Tracking how quickly your heart rebounds from a serious physical effort can help you benchmark your cardiovascular strength. Chris Crowley, coauthor of the Younger Next Year book series (written with Henry S. Lodge, M.D.), explains: "It's a common-sense correlation between your recovery rate and what kind of shape you're in." The faster your heart recovers, the fitter you are. To measure yours, warm up thoroughly, then run hard or do a hill repeat for one to two minutes. Stop and watch your heart rate monitor. As soon as your rate drops one beat, start timing. After 60 seconds, see how many beats per minute it has dropped. In general, a one-minute recovery rate in the 30s is good and 40s is great. The bigger the number, the fitter you are.Lactate Threshold
This is the point at which your body can't clear lactic acid as quickly as it's being produced. In other words, it represents the highest aerobic effort that you can sustain for a prolonged period of time — and you can improve your lactate threshold if you train hard and smart. Dr. Lodge (of the Younger Next Year series) explains a way to test yours: "Pick a day when you haven't run hard for two or three days, warm up for 10 minutes, then run the hardest pace you can sustain for half an hour, ending as strong as you started." Your average heart rate for the last 20 minutes of your run will roughly correspond to your lactate threshold. If you try the test a month later and can run it at a higher average heart rate, you've increased your lactate threshold — and your fitness.Nutrition
When it comes to losing weight, exercise alone won't cut it. "You can eat your way through any level of exercise very easily," says Dr. Lodge. The key to losing weight and still running your best: Eat fewer calories than you burn, and consume high-quality, nutrient-rich foods. These numbers will help you do that.Hunger Scale
Rating your appetite can help you reduce your calorie intake and lose weight by preventing overeating. In his book The Blue Zones, author Dan Buettner explains that the Okinawans of Japan (who live very long lives) adopt the concept of hara hachi bu ("Eat until 80 percent full"). The hunger scale is similar: On a scale of 1 to 10, where 1 is ravenous and 10 is stuffed, eat when you're at a 3 or 4, and stop when you reach a 6 or 7. Never get too hungry (or you'll eat more than you need) or too full (which means you may have consumed too many calories).Follow these eight nutrition rules for healthy eating and shrink your waistline.