I waited until the incoming wave hit the rocks. Enjoy and keep on photographing!
I learned from Andre Kertesz, the famous Hungarian Photographer, that the difference between a great shot and a mediocre shot is usually just a split second. We many times say timing is everything. This exercise is about timing and waiting for the right moment. Go and find yourself scenes where you have to wait for the right moment and then photograph, photograph and photograph.
I did this exercise at the beach. the waves were coming in and I had to wait for the right moment to press the shutter.
Enjoy and keep on photographing!