When a goal is perceived to be unreachable, no effort will be made to achieve it. Set realistic goals. Conversely goals can be set so low that you feel no challenge in achieving the goal. You may feel in this case, that setting goals has been a waste of time. Always set goals that are challenging.
Goals can be so vague that they are useless.
It is difficult to know whether vague goals have been achieved. If achievement cannot be measured, then your self-confidence will not benefit from goal setting, nor can you observe progress towards a greater goal. Set precise, quantitative goals. Goal setting can be unsystematic, sporadic and disorganized. Here goals will be forgotten, achievement of goals will not be measured and feedback will not occur in new goals.