Somebody gave an opportunity you had hoped to get to someone else.

Thoughts start popping into your head about why the person passed you over.

The only problem is that the thoughts are unconstructive.

It's natural.

What you do with those thoughts could turn into a problem.

Reject them.

If you choose to entertain them, it's like watering weeds. 

They will multiply and poison your mind.

Don't water the weeds.