Expectation is one of the most potent ingredients that determines whether at the end of the day one feels successful or defeated. Because leaders have a great deal of control over expectations for themselves and their followers it follows that leaders have a great deal of control over whether team members feel energized or demoralized.
Conventional wisdom says expectations should be set with scientific precision, just enough stretching to grow people and make progress but attainable enough to not deter However, as a leader you cannot always get it right, I know I do not.
So for me, I take a different approach. Instead of futilely seeking to find balance within each and every task, project, or strategy, I strive for balance between them. I prefer to set some goals that are 100% achievable and some that are 50% achievable instead of trying to set all goals that are 95% achievable. I just don't believe leaders can consistently and accurately set expectations with single digit precision.
Another reason to take this approach is that not every goal needs to be stretched.
I propose you take the same approach. A mix of easier goals and very challenging goals can be more rewarding and produce better results compared to trying to optimize every goal, task.