achieving goals

I've always believe human can achieve anything, once we put our mind into it. Because what's between us and our goal is only our mind. We are often motivated by the Olympic athlete's stunning record, the physicists' discovery on new particles, the artists' astonishing new creations. But recently, I discovered that some things in the world are not achievable, or rather, in the process of achieving it, we might lose things we cherish the most.
When we are in the process of achieving our goals, do we sometimes stop and think, or do we simply going forward blindly, hoping the end result would make up for the negatives we endured. Shouldn't the process be fulfilling and satisfying as well?
What would you feel if you reach the top of the mountain just to realize how lonely you really are?
After all, we might not always achieve the goals we set, but we should always grow while doing it.