The causes of AVM are not known. It is thought to be developed in utero. Some people with AVM will never have a rupture, some have multiple AVM’s, some AVM’s will Rupture causing hemorrhage/Stroke (brain), aneurysm, blood clots, and various other issues.
There is nothing you did or didn’t do which caused the AVM. Smoking, lack of exercise, or general wellness has nothing to do with whether you have an AVM or whether you have a rupture. Being in good health will help, however, with your recovery.