If you want some real motivational and headstrong music, I suggest Hatebreed or Throwdown. I know you said you can't understand hardcore music, but these band are quite easy to understand if you just listen. Hatebreed has many great songs such as Perseverance, A Call for Blood, and I Will Be Heard, along with many others. Also checkout Throwdown's Forever, or Declare Your War. This shit gets me so ****in pumped up! These are really the only bands I listen to during training.
Slipknot, Machine Head, Hatebreed, Lamb of God, Sepultura, Soulfly, The Skinflicks (oi! music kicks ass too!), Dropkick Murphys, AC DC, Motorhead, Metallica, Bootstroke, Throwdown, Carnifax, Children of Bodom, Stemm (Face the Pain is a must when working out), SOAD..There are others but i can't remember them all