Strong like Susan is phenomenal. They are all very challenging and based on reading her bio she is also a professional trainer. I first saw and read about her on youtube.com and have been hooked on her videos every since. She calls herself your youtube video trainer and she is NO JOKE!
You can read more about her HERE!
Her workouts are challenging and will leave you in a puddle of sweat! Check her out.
She is one of my fitness idols.