What a great quote to be using for a presentation about lessons from life! There are all kinds of ways you could approach your speech, incorporating the idea and intent of the quote.
Can you relate the quote to a life lesson that you have fought against learning for a long time, but have finally conceded to acquiring? Think about how hard Ray Kinsella tried to ignore the voice prompting him to build the field, but how rewarding it was when he gave in and followed the dream. You could open by comparing your experience with Ray's.
Did you have to convince others of the worth of your dream, the value of your life lesson? Lots of people, including his wife and brother, didn't understand what Ray was doing or why as he struggled to figure out what the voice was telling him. Eventually, however, they all did comprehend and appreciate the importance of what he accomplished. You could draw parallels between your experience and Ray's.
Did the accomplishment of your life lesson allow you to do something really significant for someone else? The field brought peace and reconciliation to Ray and his father. Are you able to share some type of life-changing impact that your lesson had?
It's a great starting point for your topic. Good luck!
Start out the speech with the quote, followed by your opinion towards it and continue to build on that.
Basically, put yourself in the audiance's frame of mind; make it interesting to the listener.