I actually created a profile here partially because of this, the other reason being this seems like a great community and a great place for support through some dark days. I just turned 26 about a month ago and found out back in may I had a 5.4 cm ATAA (Ascending Thoracic Aortic Aneurysm), and then found out about my Bicuspid Aortic Valve after the surgery was done and I had my Mechanical Valve put in.
My life change after surgery was rather drastic, I would believe. You're going to be very limited for the first month or so, even after. I'm six weeks out of my first surgery, four weeks out of a surgery for pericarditis. I'm still not back to normal and from what I've been reading, the standard recovery is not 6 to 8 weeks. Depending on your definition of "weight train", power squats and bench presses? I wouldn't expect to be doing those any time soon, as for the first month or so after surgery you'll feel it when you lift a grocery bag.
Pre-Surgery, I was very nervous. But I knew this had to be done, the surgical staff at the hospital was very caring. My surgeon gave me peace of mind when I asked him his track record (how many repairs he's done prior, experience, etc.) and that put me at ease a lot. But on the day of, if you're like me, you're going to be nervous and/or scared. I know I was. Post-Surgery, I felt pretty awful when I woke up. They'll have you out of bed and walking within a day (brace yourself when they turn you on your side, that was the most painful part of getting out of bed), I spent most of my time in the chair, as laying down was extremely uncomfortable. Walking isn't so bad the day after, but don't over-do it. Even six/four weeks out of surgery, I'm still pretty sore, but there are going to be good days and bad days. Some days you'll feel like a million bucks, others you'll feel like you had that million bucks put into a cannon and shot at you. I still have a lot of problems sleeping, all positions are uncomfortable and I really don't sleep for more than a few hours at a time.
Best advice I can give, which I learned the hard way: Do not over-exert yourself. You're probably going to do it at least once, and once is all it takes to realize your limitations after surgery. But in due time, of course you'll be able to do all of those things again. But don't get your hopes up, your body is going to be going through a very traumatic and very different experience, and it's going to be a bumpy road until you find a state of complete normalcy again, so buckle up.
I hope I didn't scare you, this is just what I've been experiencing and as my Surgeon told me: Every patient is different.
Good luck to you!