You have three options.

1. Try and try and try until you've let go of that excitement. The whole point is to fall asleep, and if you're too excited you will never be able to do it. This will come in time and with experience.

2. Try another technique. I had your problem and I gave up quickly on WILD. I decided to focus mainly on MILD and it works great. I can even DEILD now and have succeded in a few WILD's aswell.

3. Start meditating and combine it with step 1. By meditating frequently you learn to relax and you become used to small changes in your body. Numbing, rushing, tingling sensations won't rile you up as much and you will have an easier time WILD'ing.

You also need to wake up in the middle of a REM period when you try to WILD. Good luck!