When I undertake a Deep-Air Dive (dry or wet), I put-on my game face. I do the same thing when piloting a CCR, or when entering a Cave or Wreck (regardless of the breathing mixture being used). It's all business. I approach Deep-Air as a challenge to overcome in a similar way. I don't allow myself to have 'fun' until the dive is completed. Then I can relax and go over everything in my mind. I survived the experience.
For those interested in diving Deep-Air: get trained, get experience and get diving. Remember to tread slowly and be vigilant. Narcosis is deceptive and it awaits the unwary...