Contrary to popular belief, quitting weed is hard

I am a senior in college, and I have been smoking weed heavily for the last four years; often 3 or 4 times per day. After my supply ran out on Sunday (96 hours ago), I decided that it was time to quit. I have had multiple cravings every day and it's been very hard not to give in. All I want to do is call my dealer and pick up another bag. I've had a lack of motivation, increased agitation, headaches, and an overall feeling of lethargy. My cravings are particularly strong today, and I thought posting here would help me cope. If anyone has any advice, I'd love to hear from you.