Exercise for just 20 minutes a day - it will reduce feelings of anxiety and increase your sense of well being. Only take on what you can do. Then assertively say No. The more you practise this, the easier it becomes and the less stressed you will be. Just think of the extra spare time you will have created for yourself.
Meditation lowers blood pressure.
Just close your eyes, concentrate on an image or a sound and breathe slowly for a few minutes. Do not worry if your mind wanders, you will still feel calmer than you did before. Any short break during a hectic day helps keep stress at bay. A short walk around the block, a quick chat on the phone with a friend. Break your routine.