I would start by breathing. Three deep breathes to calm you down and make you focus. Then you will have a clearer mind. You then need to consider your tasks, what’s urgent and what can wait. You also need to consider the time you have. Anytime you feel overwhelmed – just breathe
Try to make everything ready the evening before. That way you win some time in the morning. Make sure you have a planning so you don't forget to do some things. If you want to do some relaxation exercises, you can do this when you go to the toilet. Just take a few deep breaths.
Reward yourself at the end of the day! Whether that be exercising, cooking a meal, or simply reading a chapter of a book before bed, pick something that you can look forward to for the rest of the day.
Best you can do is start your day with a healthy breakfast and 10-15 min of meditation to clear your mind. Then create a list of all the things you have to do at work and sort it, most important tasks first. Try to set an approximate time for each task, and focus on them following the schedule. Celebrate at the end of the day all accomplishments, you did a great job for sure!
Take some minutes in between work to stretch, remember to drink water, and still think positively of the smallest achievements.