I like this ad about the Lemonade Stand, because it is the opposite of what most entrepreneurs do.
Most founders would run in the house and try to make iced tea to sell to the people who ask for it. That is not a good strategy. Be like the kids: Sell your lemonade! Say No to the iced tea.
When you have enough bandwidth, add a new product (the iced tea). But give an honest effort to selling the lemonade before adding a new product or tweaking your lemonade into Arnold Palmers.