Exercise releases endorphins and will help to relieve stress. Taking a walk, or doing a favorite activity, riding a bike, or going to the gym, gardening, what ever your favorite activity might be.
B complex vitamins are the stress vitamin, the more stress, the more b vitamins you will need. Cut back on caffeine,it will only add to the problem. Increase water.
Getting a handle on to do lists, may also help. Write down what you need to do in a list, as you check those things off, you will get a sense of accomplishment. A calendar is very helpful also. Write down activities, or bills due, on one calendar, it will help to alleviate the stress of trying to remember. And kinda put things into perspective.
Are there any things that can be eliminated to reduce your "to do" list? that will also take some of the stress off of always saying yes. Leave some down time for yourself.