Not easy and impossible are two distinctly different things, however.
Along with this, here are some drills for athletic adults and youngsters to consider when they desire to improve hand eye coordination for the sake of sports performance.
Connect Four: Connect Four is a game of visual planning and organization. The hand part of hand eye coordination won't get much of a workout. However, the eye part will and that can't hurt.
Focus near and far: Quickly practice focusing on a near and then far object. Go back and forth, back and forth.
Goalie: Have someone try to throw a soft ball (like a nerf ball) by you into a real or makeshift goal. The only catch? You have to stop the ball with your hands. Depending on your performance, have the thrower move closer or further away.
Have a catch with a catch: Get a large wiffle ball, softball, or really any ball that's light colored. Then write a bunch of letters on the ball with a black marker. Next, find someone to have a catch with. As each of you is about to catch the ball, call out the last letter you see.
Have a catch with yourself: One thing you can do to improve hand eye coordination is throw a baseball up in the air repeatedly and catch it. The same goes for any ball, including a football.
Raquet sports: Ever play ping pong? Well, if you have then you know how much that sport can improve your hand eye coordination. Have to assume that raquetball is of the same ilk. Tennis too. In other words, anytime you have to react to another person's movement and a ball with your own hand, you're going to improve hand eye coordination.
Speed bag drills: Boxers have outstanding hand eye coordination simply because if they didn't they'd be unconscious a whole heckuva lot of the time. One thing they do to keep sharp is use the speed bag. You can too.
Video games: Chris Spielman, an outstanding former linebacker for the Detroit Lions, once indicated that he sometimes would work on hand eye coordination via video games. How often this occurred is unclear. What we do know is that visual perception and motor skills can be improved through the use of video games.
Wall ball: Stand in front of a flat wall with a basketball. Then begin to throw it against the wall and catch it. After you've warmed up sufficiently, begin to throw it against the wall with only one hand. Every time it bounces off the wall push it back against the wall- without catching it- with the fingertips of the same hand you threw it with. Then repeat with your non- dominant hand.
Get involved in sports, period: Virtually any sport from golf to baseball to karate will improve hand eye coordination. In fact, probably nothing will help to improve it more than a sport you attend regularly, whether it be a town sports league or something in a professional sense.
In the end, like anything else, hand eye coordination has deep roots to childhood. That said, change is possible, as is improvement with practice. Therefore, the key is to know how to practice and have the desire to do so.