3 days is a great start, brother. I think the first week is the toughest. But remember to embrace the suck. Actually take note of how bad you feel, the agitation, the sleeplessness, etc. Feel it and remember it. That is the feeling of your recovery. Can you believe it? Your body actually craving poison that WILL KILL YOU?!!!
It is crazy to think about. Then consider that nobody gets through where you are now without feeling the same way. Pretty cool to think about that...all the badass quitters fighting just as you are now. You're earning your freedom one day at a time. Well done, brother!