Positive stress! Or negative?
Even just the grammatical symbols demonstrate the difference here with the up! And the down?
Positive stress keeps us on our toes, alert and stimulated. It helps us get things done. It's the adrenalin rush we associate with fun and challenge.
The downside of this stress is when it keeps going, when it develops into negativity and causes problems. Usually because it goes on for longer and can eventually, if left, lead to burnout and breakdowns when our body can no longer cope with providing this 'fight or flight' response. We need to stop. We can re-evaluate what is going on and then find options to make effective changes so we can once again manage our life.
Even the nerves of presentations or car rallying have the inherent 'fight of flight' as an option of dealing with the threat of danger - run and refuse to continue, or fight (usually ourselves) to override the defence mechanism and take it on.
So when your heart beats faster and harder, your mouth gets dry and your hairs stand on end (because the blood goes to essential organs like heart and brain, and you get cooler) it's just your body reacting to stress and is the result of being unable to meet the demands placed on you.
That can be facing something or someone daunting (elephant charging, boss coming down the corridor, friends asking for favours or too much work on for example). Managing this is your health and well-being. It's your happiness or depression potentially, but you can manage it day to day or as an holistic change to your lifestyle or attitude.
Daily, learn to relax - be aware of your body's reactions and this alone distracts your mind from the threat and so slows down the heart, breathing, blood direction etc. Take a break and re-evaluate what is happening and why, and change it even slightly.
More long term, you need to look at your situation and environment. What is working and what's not, and why that might be. And again, change it but for a bigger or more long lasting change not a drastic one like leaving your job or family.
Writing things down or telling someone (saying it aloud) makes it more real and clear, and because you need to find the words, you clear up the issues for yourself a bit more too. Give it a try. Daily and then wider than that. It can help you take the necessary steps for a happier and healthier you!