To truly shed stress while on vacation, you need to unplug from technology. Plan ahead so your colleagues, bosses and clients know you'll be unreachable and whom to contact in your absence, and plan for your re-entry into the office, experts say. Another key tip: If you don't want to be considered reachable, don't respond to even a single e-mail. If you do, said Daniel Sieberg, writer of "The Digital Diet," "you've just opened the floodgates. You've lost that barrier -- it's gone like a sandcastle in front of the ocean. Now that person knows that you're really not on vacation."