Training is not supposed to be hard, its supposed to be fun, its supposed to be about learning how to move with ease, with fluidity, moving in new patterns that result in greater efficiency hence greater speed and endurance. If you put the cart (speed & endurance) before the horse (technique training) you will not come close to experiencing the true joy of sport, nor will you ever experience your potential in the sport.
I encourage you to play… try out the drill. Can you do it? Can you execute this simple drill that works on proper foot placement in the landing, proper weight transfer, proper coordination of the arms, correct trunk and head posture, and develops the proper drive source for a runners stride? If you are having difficulty with this drill, then what will you accomplish by heading out and just running mindless miles? Not much. Sorry, not true… you will accomplish something, you will accomplish feeling sore, perhaps even pain, and then you will have to decide whether or not to go out and subject your body to another run, and to the inevitable soreness, aches and pains that are sure to come after.
There is another way to train… training technique. I promise that in time it will open you up to the true value and meaning of sport, and it will open you up to you.