Read Gurmukh's reply:
Kegel exercises are integral to women's health before, during, and after pregnancy. Routine Kegel exercises can help a woman maintain her strength, and can also prevent medical complications after giving birth. Any woman who has had incontinence problems, or who just has minor leaking when laughing, sneezing, or jumping, will benefit from these exercises.
The easiest way to isolate the muscles is to interrupt the flow of urine. At first, if your muscles are weak, you may not be able to stop the flow completely. But if you repeat this process eight times every time you urinate, your muscles will grow stronger. You will come to know exactly what the Kegel muscles are.