I took Bobby surfing, he was about 70 & surfed when he was younger. It was a true challenge for him, a knee injury, the need to react quick in the water, the waves were strong BUT he got out there. He went for it and was intelligent enough to know his limits.
I love taking people of all ages for a lesson. It's okay to not stand up. But maybe you get past a fear of the ocean or challenge yourself with the fitness whatever it is & I truly believe what you conquer in the water will lead to overcoming something else in your life.