As a fitness trainer for more than seven years, I learned many universal truths about people and their fitness habits. Most people have a natural tendency to focus on their strengths and ignore their weaknesses.
I am as guilty of this as anyone. This is evident by looking at my scores on our department's bi-annual fitness testing. For the past three years, my strengths have improved, while I have scored lower in the areas that I truly need to improve upon.
If you struggle in any area of physical fitness (and we all do) it is imperative that you work on them now. You will want to be in the best shape of your life for the agility testing, and especially a fire academy and probationary period. Being in top shape prior to, and during, your academy or probation will make it much easier — that way you can focus more on the academics.