Positive avoidance basically suggests avoiding situations, places, events that could cause unnecessary worry, anxiety, or just be plain harmful.
It's smart for example for a recovering alcoholic to avoid the pub.
If there is positive avoidance I guess there must also be negative avoidance. Avoiding situations that may cause a level of discomfort but by entering into them there is the potential to grow, to become more resilient, to ultimately flourish.
And sometimes it's just plain obvious.
If you want to be a mountaineer, at some point you gotta start climbing mountains.