This isn't always possible, but in cases where it is it's better to find out than never know.
Don't give up at the first hurdle.
You might have many throughout your life and the trick is not to avoid, but work around them.
Don't give up just because you're not good at something.
One of my magic words comes into play here: yet.
Just because you're not there yet, doesn't mean you never will be.
Example: I've been having singing lessons and at first I was rubbish and couldn't even hold an arpedigo (a really long note). But I kept on with it for two months solid and I am now able to do them much more strongly. This, however does not give me a feasible reason to stop practising. I still practise as much as I can.
It takes practise and persistence. Persistence is carrying on in spite of what others may think or indeed say.
This might be an idea you've had or anything but the key with persistence is that you don't let anyone or anything put you off.
It is very hard to do but all you have to remember is that it's only their opinion.
*Hope this has helped. Let me know in the comments!*