As I mentioned in a recent post, there's exercising hard, and then there's exercising smart. It's not necessary to spend four hours in the gym every day to feel and see a marked improvement to your overall health. What is necessary, however, is to make sure that you are maximizing your time -- even if if is far less than four hours per day.

WebMD just listed the 7 Most Effective Exercises, along with descriptions and explanations of why each ranks so high.

7. Walking

6. Interval Training

5. Squats

4. Lunges

3. Push-ups

2. Abdominal Crunches

1. Bent-Over Row

Following most or all of these suggested exercises is a great way to ensure that you are making the most of your time spent in the gym.