The Little Engine That Could by Watty Piper

From chapters.ca:
The Little Engine That Could’s cautious little heroine in steel knows that she’s the only one left to bring all the toys on the train over the mountain in time to reach the children anxiously waiting on the other side. But can she do it? By repeating the mantra of “I think I can, I think I can,” the little engine completes her task and realizes a fundamental rule of positive thinking: you can talk yourself into feeling good as easily as you’ve talked yourself into feeling bad!