The adrenaline is your body's natural drug that, in moderation, makes you sharp, creative, and quick. It creates the feeling of excitement and exhilaration that comes from trying something new. Recognize that it also can be scary and stressful. Some stress is useful. Too much can be harmful.
Some stress provides energy.
Too much stress causes distress and can lead to burnout if done to extreme. Because that's where growth takes place. Just like a muscle gets stronger when you exercise it outside its normal range of use, you get stronger when you get out of your rut. And just like your muscles, once you stretch beyond your current capabilities, you don't ever go back to your original dimensions. As you try new things, you gain confidence.