Waterskiing rocks! It lets one look forward to and enjoy those hot days. While it's pretty physical, the water is relatively soft and doesn't hurt you too much (unless you are barefooting!). The average age of the top competitors is pretty old - I think the slalom world record holders are in their 30s. So
@Tex no excuses due to age!
Traditional waterskiing is slalom, tricks and jump. Slalom is six turns in 16.95 seconds, carved turns, G-loads (the ropes are rated for 1000 pounds!) and the winner gets the most buoys at the shortest rope. Tricks is a display of how many difficult tricks a person can do in two 20 second passes. Jump is just how far can you go off a ramp after cutting hard enough at the ramp to generate tremendous speed.
Wakeboarding is a separate sport similar to trick skiing except style is emphasized over speed. Very different feel.
Barefooting is another aspect with its version of slalom, tricks and jump.
Speed skiing is another if you have a really fast boat.
All these sports require dynamic balance and core strength - like snow skiing. To get good, you need experience. But there is some crossover with snow sports. Warren Witherall is a legendary instructor in both water and snow skiing. I've skied with Dahron Rahlves and Tamara McKinney and they are skilled waterskiers. Glen Plake is another waterski standout who we know as a snow skier. Dave Goode was on the US Ski Team and also a top competitive waterskier (as well as being a brilliant equipment designer for both sports). Lots of the good waterskiers are also phenomenal snow skiers (and vice versa).
When the snow isn't there, enjoy the water!
Eric