Missing periods due to exercise. Is this normal?

Patient: Okay, so I have adapted myself to a healthy life style. I have a personal trainer and do lots of exercise, I love it. I eat extremely healthy and regularly. In a nutshell, I have an extremely healthy lifestyle. However, ever since I have started this (July 1st) I have missed my period. Am I doing something wrong?

Doctor: Occasionally missing a period is not necessarily dangerous, but long-term amenorrhea can be. Though missed periods or am menorrhea may be due to excessive exercise. I would however advice you to do a home pregnancy test to rule out pregnancy as the cause of amenorrhea. If you are experiencing missed periods, you should consult your doctor.