It's interesting how different one can look at a situation, depending on if one just got caught up in it or if one chose for it to happen. A rather practical example of this: how would you feel if you were told you had to stay in a very shitty, dirty, disgusting, crappy apartment for a month and there was no way to get out of it? Considering that you're not given any alternatives you'll probably try to make the best of it. Now compare that to how you'd feel if you actually had to choose that crappy apartment yourself and consciously decide to live there, despite grokking its crappy nature. Speaking from personal experience, I'd try to squirm my way out of making that choice by any means possible.
I think different people handle these choices differently. People with more foresight might choose a better apartment. People with more hindsight may regret their choose more after having made it. Me, I'd probably accept whatever choice I had made in the past and go on with life. After all, regretting a choice that you made yourself is like doubting yourself. It won't lead anywhere.
On a somewhat related note, can someone with ambition ever be satisfied? They seem to be two opposite concepts to me. If you're ambitious then it's in your nature to find flaw with your current situation. The next step would be to try and improve your situation, but if you're really ambitious then you will just find another flaw that needs to be fixed. It's related to accepting/choosing in that one must choose to be ambitious, whereas one must accept to be satisfied. There's really no other way. Can you accept to be ambitious or choose to be satisfied? I don't think so.
For me the crux of ambition versus satisfaction lies in how you handle unexpected situations. What do you do when the hotel you already booked suddenly doesn't have a room for you? What do you do if a friend drops by unexpectedly? You can substitute 'What do you do' in the previous sentences with 'How would you feel' and it might make things more clear. Would you feel frustrated that things are not going according to plan (thereby defeating your ambitions), or would you just roll with it and see where the situation leads?
Some of the most (professionally) successful people I've met are also the ones who hate unexpected situations the most. But if I'm any good at detecting happiness in people, then I'd say that people of a more accepting nature are more happy. Ambitious people would challenge that, of course. It's just one more thing that would improve their life if they choose not to accept that statement. And happy people would gladly accept.
I think it's fairly obvious which type I am. Which type are you?