Crossword puzzle clue "regret one has about not doing glute exercises"

Regret one has about not doing glute exercises?

Showing agility, as when doing floor exercises

"'I've been doing exercises to strengthen my core muscles,' Brendan said obliquely," e.g.

Expressed regret for what one has done

Feeling regret about not trading one last stock?

Stop doing what you're doing

"Just keep doing what you're doing, suitcases!"

"___ job's worth doing, it's worth doing well": 2 wds.