So I am making a solution to clarify what a drill is, the reason the achievement is called 30 seconds of fun is because drills are usually around 30 seconds long.
Every work-out is compressed of drills, each drill is on average of 30 seconds for instance I am on MOSSA FIGHT and im at 26:35 and im on drill 54, which means every drill has been a average of 30 seconds.
There is no fastest way to unlock this, you must simply work out and the more you work-out youll get closer to this achievement. The only thing you can really do is make it easier on yourself by choosing a work-out you can handle. Going for the "This is my Everest achievement" should help going for this if not already unlocking this first.
As there is a progression bar when looking at the achievement you can look at how many drills you have done on a single work-out by pressing start in the middle of the work-out it will be in the bottom left hand corner.
Have fun, and good luck!