This article was written by Monica Morris and wikiHow Staff Writer, Jennifer Mueller, JD. Monica Morris is an ACE (American Council on Exercise) Certified Personal Trainer based in the San Francisco Bay Area. With over 15 years of fitness training experience, Monica started her own physical training practice and earned her ACE Certification in 2017. Her workouts emphasize proper warm-up, cool-down, and stretching techniques. This article has been viewed 2,377 times.