What did Milo think was the greatest waste of time? Why?

Milo is bored by pretty much everything in life. He always wishes he were somewhere else. When he is indoors, he wants to be outside, and when he is outdoors, he wants to go back in. Milo does not feel like doing anything with his life, as absolutely nothing interests him in the slightest. Numerous toys, games, books, and tools all lie around in his bedroom, underused and gathering dust.
School is probably the worst place on earth for someone suffering from perennial boredom. Spending time in class is absolute hell for Milo. Solving problems, subtracting turnips from turnips, knowing where Ethiopia is, and learning how to spell "February" is all just a complete waste of time for him. But for Milo, the biggest waste of time of all is the process of seeking knowledge. Thankfully, this attitude begins to change after he revs up his toy car and drives through the phantom tollbooth.