Exercising and staying healthy can improve your background chances of fertility. Having said that though, if you overdo it to the point that you start missing your menses then this could indicate that you are not ovulating regularly spontaneously and this would then reduce your chances of conceiving. Too much of a good thing is not helpful.
Moderation is best. You should check that you are ovulating spontaneously during your fertile days. If you are ovulating regularly then it is fine to continue with your strenuous physical exercises.
If you are not ovulating, then you should stop the exercises or cut down and see your gynaecologist as soon as possible who should be able to give you ovulation medication and to exclude other causes of infertility.
