It is a shock to discover that you have an aneurysm. I was told I had a 3.8 cm infra renal aneurysm 13 years ago. It is now 5.0 cm and I am 80. I lead an active life with no limitations. With my complicated anatomy, the surgeon wants to wait until it reaches 6.0 cm before repair.
Sometimes they grow slow or not at all and sometimes they grow fast and need to be repaired. The repair has risks as well as benefits and most cardiologists say the the risks outweigh the benefits when the size is under 5.5 cm for men and 5.0 for women, It also depends on the particular anatomy as well as your family history and your life habits. I was a smoker and stopped when I learned I had the aneurysm. In the past 13 years, I have kept my blood pressure low with medications, exercised 5 days a week on a treadmill and monitored the growth yearly and now every 6 months sometimes with ultrasound and now with CT scans.
My advise is to find a cardiologist or cardiac surgeon you trust and discuss what is the best option for you. If you don't like the advise, get a second opinion. Good luck .