It depends on goal and one's committment. However, these two things i.e. goal and one's committment, are complementary to each other, the goal should be achievabale. For instance, if someone wants big rivers like 'the Mahakali' to reverse its stream, one rearly succeed in reaching the goal. If one considres feasible scope while determing the goal, and make viable goals, and exert oneself to achieve this, they won't have to stop trying or move on towards another option later on. Sometimes what happen is even with these careful consideration, one may find hard to get the desired goal. In such a situation one shouldn't give up, but rather keep trying, and remember Napoleon Hill's great quote 'Edison failed 10,000 times before he made the electric light. Don't be discouraged if you fail a few times.'