The down side of adrenaline is that it can undo our powers of concentration and memory and may even cause muscle tremors.
Stress closes down the lens of our attention.
The suggestion of "Relax, don't take life so seriously" is easily prescribed but hard to follow. Seek out and practice stress reduction techniques.
Based on material from "How to Boost your brain-power" by Roger Yepson published by Rodale press 1987.