The couch stretch is a hip opener.  Use it for tight, tight, tight hip flexors. If you sit all day with a desk job, it's essential. 2:00 is minimum Rx but you should do it more if you sit more then 4 hours a day. Also read Kelly's other book Deskbound:

Don't hold your breath (on any mobilization). Maintain and breathe for at least 2:00 seconds each side.  The couch stretch is also a good one to do if you have lower back pain. A slight pelvic tilt can compress the lumbar spine and cause you to have to rest for extended periods of time. Watch the video above for the 2 finger rule which I explain.

Number two is the hip hinge and number three is dealing with your posture.

Hip hinging is vital to any lower body exercise. And it is vital to movement in life and all sports.

As I mention in the video hip, knee, ankle, neck, shoulder, low back, elbow, wrist pain doesn't just start from one episode. Unless it's a blunt force trauma injury. It happens over years and Decades of crappy movement. But you must be aware of that movement now and save yourself the pain of having to go through that later by doing these types of things that are known as mobilizations and Primal movements like the hip hinge.
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Rest of the pre-workouts