La vida de j. r. martínez cambió para siempre en 2003 cuando sufrió un accidente en irak y se quemó más del 40% de su cuerpo. j. r. martínez decidió usar su accidente como una oportunidad para ayudar a otros.

If you want us to translate it the translation is -

The life of J.R. Martinez changed forever in 2003, when he suffered an accident in Iraq, burning over 40% of his body. J.R. Martinez decided to use his accident as an opportunity to help others.

retos is the answer because retos is challenges

when you are going to explain a procedure,   the first thing to do is to name the parts or the apparatus you are going to describe in terms of how it or they function. also it is important to know who is going to operate it and the abilities this man/woman requires to manage it.