Following up on yesterday's post regarding train idioms and allusions. The first two, "the little engine that could" and "I think I can" come from a wildly popular children's book that just about everybody in North America has grown up with.
In the story, a little blue pony engine--a very small train engine--manages to haul a load of toys over a mountain. As he goes up the grade (trains in children's stories can talk) he calls out "I think I can!" again and again. When he reaches the top of the mountain and starts heading down the other side, he says "I thought I could." Both sentences repeated sound a bit like a steam train in motion, so saying them or hearing them said is appealing. Try it! Good for developing pronunciation! The moral of the story is to keep trying and you may succeed even if the job looks tough.
The complete story, in the two most famous editions, is online here.
Or listen here.