My journey through positive thinking

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitvely tell which switch is connected to each light bulb?

Answer: Turn on the first two switches. Leave them on for five minutes. Once five minutes have passed, turn off the second switch, leaving one switch on. Now go through the door. The light that is connected to the second switch. Whichever of the other two is warm to the touch is connected to the second switch. The bulb that is cold is connected switch that was turned on. Thought this brain teaser hard?