You will achieve what you fully and confidently expect to achieve, but usually not on the first attempt. The only real failure is an unwillingness to persevere until that last attempt, the one that brings success.
Each time you fall short of the goal is actually a solid step in the direction of that goal. Each attempt makes you that much more prepared to take the next step. You cannot know in advance just how many attempts it will take. Yet you can be sure that each attempt will bring you one step closer to success.
The world is full of great achievements from inventors, musicians, authors, scientists, salespeople, artists, engineers and many others who fell short on the first attempt. How fortunate we are that they had the foresight to keep going until they got it right.
Stopping before you reach the goal does not make the discouragement go away. All it does is make the discouragement permanent. Instead, keep going, keep making the attempt, until you make that last, fulfilling attempt that brings the success you desire.