Agree as always with @moonboy, being 50 and active works in your favor. Mine was 5.2 when found at 54 yo, I was very active and in good shape, also with family history. My cardiologist who is an expert in aortic diseases told me to stay active, but eliminate any exercise that leads to hold your breath or grunt (as Moonboy mentioned, heavy weights, pushups and even crunches ) but walking and even lightly strenuous aerobic activities were fine. Is not the HR but the BP that is a problem, holding your breath makes your BP spike a lot for a few seconds but even those few seconds can be disastrous.

My family history, size of my aneurysm (especially compared to body size), and my good physical shape led my surgeon to recommend repair as soon as I could. Had my surgery 2 months later. It is tough as Moonboy says but being in good shape will help you get through it fairly easily. I was in the hospital for 5 days, back to work in 3 weeks. It is likely the recommendation for you will be surgery sooner than later.

Keep taking care of your body, all the best