A quick paddle
Not quite swimming the English Channel I know, but our monthly paddle certainly gets the blood pumping especially in the winter months; even the dog likes it. We always slip on some flip flops, those pebbles are murder, but they can get dragged off when rough. It's all part of the fun.
An easy way to put a smile on ones face, when the briny is not icing your veins. Good for the circulation too.