Morning Sickness and Work :/

I'm in my first trimester, 7 weeks, and have had on and off nausea for a week or so. Also have had constipation, tiredness, and cravings not conducive to healthy diet. This is my first pregnancy and luckily I have been out of work for two weeks for the holidays...meaning I'm allowed to lay in bed and be miserable as needed. I'm scared that my morning sickness symptoms will continue and I won't be able to hold it together at work (40 hr work week with an hour commute each way on the train!!!) What's the best way to approach morning sickness at work?