The theme that can be found in both "If" and The Jungle Book by Rudyard Kipling is that enduring hard times strengthens character.
This is because, in IF and Jungle Book, there are circumstances that come up against the protagonists and other minor characters that sees hard times test their character and they finally triumphing and having their character strengthened.
My biggest goal in life so far is being able to make my mom/family happy. My setbacks are usually things that I do that are not so good and I disappoint. I just want another chance you know? A chance to go and stop those things.