grab your ass with both hands

To take control of your situation.

Imagine you are stuck and would push ahead with your hands. Now imagine you are grabbing your ass with both hands to push yourself along.

Or grabbing your ass with both hands to lift yourself out of a problem.

Similar to pulling yourself up by your bootstraps, except more evocative.

My crisis-prone neighbor was whining about her latest self-inflicted fiasco.

I told her "grab your ass with both hands" and went out for a beer with my friends.