weak points

When I was 10 years old, I have been an elementary student, and then, I played tag with my friends. Those days, I had confidence of my physical strength(I played kendo. so I have this confidence). But I was not good condition. So I was catched easily. And my friend say me " your physical strength is so "cheap"!". I wanted to be angry and say him "My condition is not good today". (73/7020 words)