Are my ideas really 'mine'?
Well, to assess something as mine is to be possessive; and possessive is contradictory too benevolence. In other words, Taken, and Given, are the two main ideas given within this context. Give is to lack control in the exchange, to take is to assess control, so I'm going to postulate that when you say "are these thoughts mine?" You mean to incline in a form of possessive behaviour, to assess control over a thought. Likewise, to assess control over a thing, whether it be something or someone else, is indicative of free will, so for the sake of simplifying things (and my argument
:P) i'm just going to say that free will exists in this scenario.
Now to take control of something in my belief is to control its aspects, or its properties. With that established, we can now take a look at the scenario. This scenario you proposed:
"do I take credit for my athletic abilities?"
Well, the ability was henceforth "given" to you. That illustrates a lack of control. However, this ability is constrained by a parameter, specifically athleticism. In other words, you need a use to portray your ability. This use is considered possessive, and non reliant on given factors.
This begs the question: If I put my abilities to use, do I control them?
Well, I don't really know. Maybe this helped a little bit though.