Many years ago, I took my first diving lesson in a pool. It wasn't an easy first step for me, I seemed to panic under water for extended times.
It's was a weird feeling but I knew that to overcome my anxiety I needed to practice and train to remain calm. This is exactly what I did and my patience paid off one sunny morning.
Since then, I've undertaken numerous diving courses and enjoy the open waters. If you're scared just like I was, take a deep breath and take your time.