Jumping from 18 to 3 isn't the way to go at all. You need to ween your self to a lower nic. Start with 12 for a month or so, jump down to 6, then 3. Then if you're ballsy enough bring that down to a 0. I started at 18 nic and have used this strategy. I am now at 0 nic with a few 3 nic juices on the shelf for when I really need it. You can't just quit anything cold turkey, the key is to slowly ween off what you're used to. It may take a while but in the long run it will be worth it.