Don't think you can do this sucker cold turkey.

Training
With over 6 miles of trail and over 6000' of elevation gain to an altitude of 13770' above sea-level, you'll want to train rigorously, at high alititudes, if possible. Here are some good training ideas

• Hiking (Obviously, this is the best training.)
  
• Rock Climbing (Keep in mind you need to be very comfortable with a 5.5 in order to summit.)
  
• Stair Laps (This will help prepare your knees for the beating they will get on both the ascent and descent. It is also good cardio-vascular training. Try the local football stadium.)
• Jogging (To maximize your workout, throw on your backpack with some weight in it so your body can get accostomed to it.)
• Biking (Find some hills. Your legs may hate you now, but you'll be thankful later.)

Permits
All that inevitable red tape.

• $25 Grand Teton Park Pass (This 7-day pass is a requirement for entrance to the park. If you plan on frequenting the park, you may want to buy a year pass for $40. It is good for Yellowstone too.)
  
• $25 Backcountry Camping Permit (Only necessary if you are going to be making the climb over two days or more. These can be obtained at the Jenny's Lake Ranger Station.)