If you feel tense, make sure you consciously breathe in and out slowly and steadily to combat the shallow breathing and breath holding we tend towards when anxious.
Maintain good posture. You spend most of your day sitting or standing. If your spine isn't’ in proper alignment, you will strain your back and neck. If you slouch while sitting you will compress your insides, including your diaphragm, and will breath shallowly.
To loosen up the neck, where many people carry their stress - Stand or sit up straight with the bottom of your spine turned under. (Do not arch your back) Let your head fall forward, keeping the neck and shoulders relaxed. Slowly swing your head to one side, then let it drop and swing to the other side.
While doing stationary exercises such as riding a stationary bike or an elliptical trainer, watching TV can make exercise more fun.
For non-stationary exercises such as walking, listening to music or listening to audiobooks may help pass the time.