Many top athletes and thriving business people know that the key to their motivation, success, confidence, and determination stems from setting Specific-Measureable-Affirmative-Realistic -Timed (SMART) goals. Setting goals in this way not only create direction in life but also reinforce the "how" in getting there. Research by Carol Dweck Ph.D. has revealed that highly successful people set reasonable and manageable goals for themselves in order to push their actions into success. She also found that individuals who were less successful, more often depressed, and less likely to challenge themselves usually set insurmountable goals for themselves. It seems that those who know how to live their lives in a successful way are more willing to take the steps in-between than those who are not. 
Setting long term and short term goals is important. If we look at Dr. Dweck's findings and think about these types of goals we may come to a fairly convenient conclusion: Setting long term goals will help us see where we would like to be but reaching the short term goals on the way will help us determine how we get there, what it will take in effort and commitment, and help us to remain motivated by smaller achievement.
It is also important to set performance and outcome goals. An outcome goal is usually the "go-to" goal that everyone thinks about - "I want to be able to do a 'real' push-up" - whereas the performance goal is usually the details that are needed and should not be overlooked -

1.) "I need to work on keeping my body flat as a board and holding that position. I can flex my abs, glutes, legs, and lower back while receiving feedback from my trainer."

2.) "I need to work on even distribution between my arms as they push and make sure they stay in the same plane. I can push slowly and remain aware of what my arms and shoulders are doing while receiving feedback from my trainer that everything stays in line."

Doing a "real" push-up within a few weeks but having it hurt you is a lot less rewarding than doing a "real" push-up within a month that looks dynamite and makes you feel in control, balanced, and strong.
So how should goals be set with all of these different kinds of goals and information?
The first step is to ask yourself some personal questions:

1.) Is this goal something I really want or is it for something or someone else?
a. Goals for yourself are much more rewarding and you remain more focused, motivated, and determined while pursuing them.
2.) Why is this goal important to me?
3.) What skills, resources, and knowledge will be needed to achieve this goal?
a. Congratulations! For many of you a personal trainer is a vital piece of the puzzle.
4.) What is my level of commitment to this goal (or to this exercise regime)?
5.) What level of performance am I aiming for (exercise competition, adult league, Boston marathon, etc.)?
6.) Does this goal fit my overall life goal?
Answering these questions before you begin will ensure that the goal you have adopted is the one for you.
Next, make sure you set specific and measureable goals. Write them down and be precise; set dates, times, and amounts in order to help ensure progress. Instead of a vague statement like "get in shape" establish criterion that will help you to see development and improvement - "I will be able to do 25 squats with perfect form after 2 months." Also set the goals to a reasonable expectation for yourself but also one that will force you to challenge yourself. If 25 perfect squats sounds like something you could do today or tomorrow, set a more challenging goal. If 25 perfect squats seems to be something that you wouldn't be able to do without some serious support, set your standards lower.
Write the goals in a positive statement that you keep with you or somewhere you will often see. The mirror in the bathroom is a great place to see your own motivating words and goals. Think of places where it would make a difference to you and make that your go-to place for motivation: on the refrigerator, in your car, in your wallet, next to your bed. It is also a wonderful experience of accomplishment and satisfaction when you complete a goal. Reward yourself for accomplishments accordingly.
Finally, be sure to be the master of your own goals. If something obstructs your ability to complete a goal, don't beat yourself up about it - make the necessary adjustments and move forward. I have personally worked with several individuals who had followed all of the necessary steps to success but fell short because of personal loss and pain that was completely unrelated to their goal. They started to punish themselves making statements like "everything is falling apart" and "I can't catch a break" and "I can't do anything right" before stepping back and realizing that life is never as easy as a plan.