Man versus Self
Internal conflict. Not all conflict involves other people. Sometimes people are their own worst enemies. An internal conflict is a good test of a character’s values. Does he give in to temptation or rise above it? Does he demand the most from himself or settle for something less? Does he even bother to struggle? The internal conflicts of a character and how they are resolved are good clues to the character’s inner strength.
"Often, more than one kind of conflict is taking place at the same time. In every case, however, the existence of conflict enhances the reader’s understanding of a character and creates the suspense and interest that make you want to continue reading."
As confirmation, I checked to see what Sparknotes had to say. This is a quote from their site: "The major conflict in The Secret Garden is between each character and his own negative thoughts."