Commuting/utility cycling/touring requires a completely different mindset than recreational cycling. Alot of it has to do w/packing, clothing choices, weather, etc. Like the above poster says it does take time to adjust physically and emotionally.

Your consumption of carbs/water needs to increase. Sources like brown rice, oatmeal, honey, etc. Myself, in addtion to the aforementioned carb sources I take a powdered protien/carb supplement and monitor my moods. If I find myself getting irritated easily I take a couple of days off the bike. You'll be fine. Just take your time.