In order to get pregnant, your tubes cannot be blocked, you must be ovulating and your husband must have reasonably good sperm. Having regular periods probably implies that you ovulate but you cannot be sure unless you test for this using urine ovulation test kits during your fertile period.
Some women who undertake strenuous exercise may not ovulate at all and that may be the cause of not being able to conceive. If you are found to be ovulating regularly every month then there is no reason why you have to exercise less as the other factors may be the cause. Regular exercise is recommended for women who are trying to conceive in order to stay healthy.
Tubal patency will have to be formally assessed via a HSG (hysterosalpingography). Your husband can submit his sperm sample after 3 days of abstinence.