Pace yourself: you can only do what you can do. Stressing out over all you have to do isn't going to get it accomplished. Prioritize your workload and work at a pace that is balanced. Don't burn yourself out by not taking breaks or multi-tasking to the point that you are actually working less efficiently.
Set aside time for yourself: not only at work but also at home. Allocate time for you to do things you're passionate about, hobbies, exercise, or anything else that takes your mind off of work and responsibilities.
Allow for moments to empty your mind: spend time in prayer just listening. Allow for time of silence so you can feel peace in your mind and calm in your heart rate. Setting time aside to empty your mind from the craziness of your day is going to be a time of refueling.
Be thankful for all things: the more you can go through your day being thankful, the easier it will be to get over obstacles that come your way. You will definitely be a much happier person if you can be thankful in all things, no matter how small.