Limiting Beliefs vs. Reality

Where is the line drawn between limiting beliefs and real impossibilities? For example, I’m am not going to make the Olympic swimming team. I’m a great swimmer, swam competitive for almost 15 years, it’s not going to happen regardless of mindset, training, etc. I’m just too old at..ahem..36. I say this tongue in cheek a bit, but it is true, that ship has sailed.

An extreme example, but the easiest place is to start at an extreme and refine from there. So as I refine away from the obvious like the above, it starts to get grey. There are for sure things I know I can do, things l know I can’t do, and a ton in the middle. Will I make $1M this year…no, but I feel that the potential is there in the future. So along with impossible goals, where does the limiting beliefs transition into “that is just plain impossible, you will not be part of NASA’s next moon mission,” etc. because I feel that there are very real situations that will not come to fruition despite the hardest efforts.

Can I get some help on determining when an impossible goal is a pipe dream instead of something that is attainable with proper focus and action?

Some sample models would help too as I am having trouble populating a decent model. Thanks.