This quote seems to express what Holden probably thinks about his destiny. He has probably realized that this is his life, and he wants to only live on his terms. This quote from the Gita seems to be saying that you shouldn't be living your life under someone else's control. That when you start living your life under someone else's ideals and rules, you're no longer living your life. I think Holden has this attitude in his personality. We know that he's been kicked out of many schools, so it seems like he has felt a need to live his life based on what he wants to do, not others. I think this part of his personality makes him an exciting and pretty cool person because I think he's really trying to live his life to fulfillment, not just someone else's expectation.
"What each must seek in his life never was on land or sea. It is something out of his own unique potentiality for experience, something that never has been and never could have been experienced by anyone else." (Joseph Campbell)
I think this quote from Joseph Campbell also expresses what Holden may believe about life. I think he believes that each life is a very unique experience, and it's not meant to be lived by anyone else. He seems to be living his life like he knows that there's no time to worry about people trying to tell him how he should be living.