Day 1 is always the hardest I think but the best day because you have made a decision that will change your life for the better. I know that when you start off on your quest that you doubt your decision, it soon passes and with knowledge and support from forums like this one you will be soon posting about your first few days before you know it, it will be about your 1st month.
I have had some really bad days and I've come on here and read posts and felt so much better and able to cope. I'm reading how I felt through other peoples posts and I know I'm not on my own. It helps even on good days I like to see how everyone is getting on and share my good moments.