Like you, I was very healthy - into fitness big time, ate healthfully, only drank wine on occasion, never smoked, not a lot of stress, low BP, etc.... you get the picture. After a bout with the flu, I developed SVT with PVC's. Had all the tests, was reassured that these were benign and I resumed my life as best I could but the SVT's were hard to live with. Had an ablation and my PVC's got worse post-procedure.
Despite feeling pretty crappy at times, I continued to do my thing. I was no longer running 8 minute miles (more like 11 minute) and had to stop often but I wasn't going to let the arrhythmia take over my life (it can do that if you allow it to). Taking back control is probably the best treatment.
I had my ablation in January and by the end of May was still in almost constant trigeminy. The first of June my heart finally started to settle down and I have been in sinus rhythm for about a month now. I have no idea why - haven't done anything different. It could be my heart has finally healed from the ablation but I never had my PVC's ablated. It could be a temporary reprieve but I am extremely grateful I can tell you that.
You may want to speak to your doctor about your options. If you are athletic, beta blockers are hard to tolerate but calcium channel blockers can be a pretty good alternative.
You're not alone! I'm 32 and my career is in the fitness industry. I've been having PACs for a year and half and was diagnosed with them officially late last year. I've seen two different cardiologists (one who specialized in electrophysiology) and both told me the condition is benign. Your cardiologist may consider a beta-blocker, or cardiac ablasion, or nothing at all. I also wondered if it was something I did, but it's not. I was told that it's a condition that may go away, but it may not. If you've seen a cardiologist and you've been cleared, then it's just a matter of not allowing worry and anxiety to immobilize you--a tough job! I've discovered that when I have a PAC and start to fret about it, it makes it even worse. When I decide not to let them worry me, I have them less often. Keep exercising--my cardiologist said that was very necessary!
I'm 21 and was just diagnosed with PAC's and PVC's, with medication mine have been more under control and I really try and focus on what my triggers are and trying to find those so I can avoid, for some people its certain foods or more stress.
I don't think its something you did wrong in the way you've lived your life when it comes to your health, PAC's are something that just happens.