Ahhh what a hip opener!
Lizard Pose or Utthan Pristhasana works deep into the hip flexor and groin muscles, both strengthening and lengthening them at the same time. There are many, many variations and different ways that you can use props in this asana in order to make yourself feel comfortable but invigorated at the same time.
We hold a lot of emotion in our hips, and particularly when we are stressed we have a reflex that automatically uses the full plethora of hip flexor muscles to pull your knees up towards your chest. Unfortunately, for those who sit regularly we are more at risk of this reflex taking over because our legs are already in the starting position when stress starts to kick in.
It's important to remember that there is a difference to good and bad pain, and in particular in Lizard Pose it's really important to listen to your body and feel which one it is, prop your back knee onto a bolster/pillow/blanket or place your elbows on a block/pillow/bolster if necessary to alleviate any 'bad' pain. Take deep breaths and give your muscles the chance to relax before you come out of the pose.
I recommend, similar to pigeon pose, to hold this one for around 10 deep breaths as a minimum, if not more, the hip flexors are tough muscles and don't like being stretched so the longer you breathe into this pose the more benefits you will see, and quicker.
Like always, make sure to only do what you feel comfortable with within reason. It's your body and you want to treat it like gold!
Here are a few variations for you to try at home...
Variation 1: Extra Tight Hips
Variation 2: Tight Hips
Variation 3: A little bit stronger...
For this final variation, if you want to make the stretch stronger you can let you knee fall out to the side. This adds a little bit more punch and stretch into your front hip.