A lot of individuals focus all of their efforts on going one direction without even knowing what they are doing. Yes, they know they are running, biking, walking, swimming, but they do not really concentrate on knowing they are going one direction and there is not lateral motion involved. If your goal is to be proficient in that one plane of motion, then go for it, but if you want to play a simple game of dodge ball, tennis or even basketball, you may be in for a world of hurt, especially if you are not used to moving side to side, in angles, etc. This where injuries can happen, especially groin, knee, ankle and hip injuries.
What is one to do? One of the best things you can do is start working on your agility, balance and stabilization, and working on compound functional movements. If this is puzzling you, you can look at ton of videos, but also hire a fitness professional or Portland personal trainer to show you how to do a ton of exercises correctly.
Being able to move in all the planes of motion is not only important in sport, but it is something we must do in our daily lives. When we get out of car, it is an awkward movement: we need to kick one leg out, squat up and to the side, get out other leg out, grab our bags (if any) and then close the door. That is a lot of steps involved in just getting out of our car. If we were to think of all the things we do and breakdown the steps into action movements, you would be amazed on what muscles are involved and the weird angles we put ourselves into and out of.