warm-up: learn to isolate the 1st chakra area
Sit in a comfortable upright position, chin slightly tucked.
Bring the hands out slightly wider than the chest, palms facing each other.
Slowly bring the hands together as you contract the anal sphincter. Focus -- this is the only place you want to squeeze! It's not the entire pelvic floor.
It can be nice to listen to some first-chakra-specific music while you do this. I like this song.