The increasing rate of diabetes and weight gain among children is a great example of why a good diet along with an exercise program is important. For every 10 pounds overweight you are your body takes serious abuse. Those 10 pounds affect your knees with 50 pounds of force. Looking at high blood pressure and heart problems is another issue associated with poor physical fitness. You may not be able to stop these from developing as you age but you can slow the progression of many diseases. It's not necessary to have a serious routine but even a program that has weight lifting and cardio walking will be a huge step in the right direction. Always remember that you cannot bank exercise. Keep trying and if you feel that you have stopped or slowed down in your training don't beat yourself up. All highways have U-TURNS on them so people can get back on track. Take that U-TURN and get things going in the right direction.
In general meaning, physical fitness is a general state of a good physical health. Obtaining a physical fitness is a result of certain great physical activity, proper nutrition and diet and most important is the proper course of physical recovery which is rest. In a nutshell, physical fitness is the fine- tuning of the human body to perform and work well.