Today is where the rubber meets the road. You very well may have stepped out into uncertain waters. You may be asking yourself if you're going to make it through the next 3 weeks? I personally know the first few days seem to be the hardest. Your flesh will be screaming. You may experience a few headaches, strong hunger pains, and maybe a little dizziness, especially if you have drastically changed your diet. Our carnal human nature is extremely selfish and is always contrary to what God wants.
Don't be discouraged! Press into the pain as we say. And let me encourage you. Hebrews 11:6 says, "Without faith it is impossible to please Him (God). For he who comes to God must believe that He IS, and that He is a rewarder of those who diligently seek Him."
Fasting is an act of faith and a way to diligently seek God. You WILL be found by Him!
See this link for a Fasting Guide that will help you gain greater insight into all kinds of fasts. Also, I encourage you to visit http://www.awake21.org/resources for daily devotionals to go along with your SOAP.
I'm believing for supernatural breakthroughs and deliverance for you. Watch what God is going to do for you as you seek him diligently!