Before starting your exercise, make sure about these things:
Wear shoes that fit well and are capable for providing the right kind of support for your activities and body type.
Wear appropriate exercise clothing.Fabrics that absorb sweat;loose-fitting light weight cotton is also fine.
During the exercise, you should stop exercising right away if you:
Have pain or pressure in the left or middle part of your chest,or in the left side of your neck,left shoulder or left arm.
Feel dizzy or sick
Break out in a cold sweat
Have muscle cramps
Feel sharp pain in your joints,feet,ankles,or bones
Notice that heart starts racing or beating irregularly
The most important is to know your limits and your needs when you do your exercise.Stop forcing yourself to do exercise you hare,and do what makes you feel peaceful,clear and joyful!