这里的present themselves怎么样理解

Nothing lay ahead us but exertion,struggle, and perverance.Those who are able to took advantage of the oportunities for success and happiness that present themselves.

题主这句话有点错误，原句应该是：Those who are able took advantage of the opportunities for success and happiness that present themselves.

这里的present代表（机会或问题）产生，意料之外出现 ，that present themselves做定语从句修饰opportunities，themselves指的是opportunities。在这里可以理解为意料之外出现的机会（有稍纵即逝的意思）。