Caroline
My husband was diagnosed with a heart murmur as a small child & continued to live a normal life until a visit to the doctor for flu 6 years ago (at the age of 56 yrs) who refered him to a heart specialist. As a result, he had to have the right mitral valve repaired and has enjoyed excellent health since. He never had any symptoms and lead a normal life in every way. I would advise you to keep the problem in mind, but not to make a big issue of it unless symptoms presenting indicate something is amiss. I am sure your doctor will have this condition noted on his health chart. My husband enjoyed sport & it never interferred with his life whatsoever. Hope this helps.