Upper Body Exercise B: Reverse Dips

You should start with the modified version of the exercise as demonstrated. Make sure you drop your butt straight down staying as close to the bench or chair as possible and only go far enough for your elbow joint to be at 90 degrees.
As with all the exercises in the program, it is crucial that you maintain good/perfect form on every repetition.
This may challenge your concentration, but improved concentration makes for a more competitive athlete!