First of all, you might want to remember that failure is a critical part of this formula. Every "successful" person I know has experienced some failure. There do appear to be some exceptions, like Ron Howard. I mean, here is a guy that was a celebrity continuously from the age of six, married his high school sweetheart at the age of 21, has 4 children and as far as I know has never struggled with alcohol or drugs.
I admire Mr. Howard, and it is difficult for me to compare my life to his. I have many more wrong turns and times where my life was not going in the direction I wanted. I accept this and believe that, unfortunately, Mr. Howard is the exception rather than the rule. Most people, including successful people, are like me and have setbacks and times where their life is going in a direction they would like to change.
This brings us to where I was thinking about a difference between these other successful people and those who have less success. The successful people realize that even when their life takes an unexpected turn that if they follow their plan and take actions to improve that they can depend on the fact that they can improve their situation. They may not be able to predict exactly when things will improve, though they can be confident and depend on the fact that it will improve.
Another way to think about it is like flipping a coin. When flipping a coin it is not possible to predict what will be the result. Each flip of the coin is a new flip and there should be about a 50/50 chance of either heads or tails showing up. Although it is not predictable, it is dependable that if you flip the coin 100 times that, on average there will most likely be a 50/50 distribution of heads and tails. Of course it is possible to flip 100 time all heads or all tails, though that is going to happen extremely few times.
The same goes for being successful. If you have a quality goal, take positive actions towards your goal, you may not be able to predict if you will receive the results we want. Maybe you have a 70% chance of getting the result you want. What is dependable is that if you repeat this activity 100 times, that you can depend on the fact that more than likely you will get the results we want.
Try and keep that in mind when you are feeling down and think you are failing. Review your goals, check that your actions are moving you closer towards your goal, and assuming these are true, then realize you can depend on the fact that a little failure is OK because even if you can't predict exactly when you will succeed, you can depend on the fact that you will eventually success.