There is one school of thought that says set the bar so high that when you only achieve part of it that you are way further along than you would have been otherwise. Not sure that is a sound approach. Why "strive" for something that we know is out of reach so we can hopefully hit something a little more reasonable that we weren't able to quantify in advance?
Why not spend a little extra effort actually determining what it is that we want to achieve (it can still be a small stretch for us) so that we can focus our efforts on working toward and attaining that? This would be a victory and not a "settle for."
We know that when we really don't believe that something will happen that we don't work quite as hard at it. If we really can't see ourselves achieving something, we have a tendency to work just a little less hard because we don't see it happening anyway.
We hear stories of people achieving great things and rising from very simple circumstances to fantastic achievements, yet we don;t see that happening for ourselves. We would like to think that it could but we really don't earnestly believe that anything like that is possible. Belief goes a very long way toward making goals happen.
It's easy to set very large goals - unrealistic ones really. Drop 30 pounds in a year when we have struggled to lose just 5 pounds at the most at any other time, double the amount of sales made a year earlier without a solid plan or new service to make that very realistic, win a sales award that is based on additional factors besides just performance, swim a certain distance such a mile or more when we have trouble just doing a single lap, compete in and finish a triathlon when we have yet to enter our first one, qualify for the Boston marathon (without ever having run any distance close to this so far), and other very auspicious but overly-reaching goals are not something we can see ourselves really doing.
While we might wish that something would happen - such as winning the lottery, having a very lucrative situation come our way, or win an achievement that ir normally takes many more years of experience to achieve - we really don't expect that it will. It's just that, a wish.
That's the real key to setting goals and then working to achieve them. They have to be based on our frame of experience so that we can believe that we can make them happen. Goals have to inspire us if we expect that we will work hard to achieve them and not just give up after a brief period because they look so far beyond what we think we can do. The only way for goals to inspire us is for us to believe that we have a chance of actually attaining them. they will hold our interest, stimulate our imagination, and create the right kind of drive for us to work toward making it happen.
We should not be setting goals so that they will sound impressive or win praise from others. Goals are personal.