Try keeping this in mind on those days... If I was to leave this world today would I be happy with the life I have lead? Have I accomplished all that I could? Have you left a positive mark on the world? Perhaps given more then you have received? How about done some things that you never thought you could do that once you accomplished then felt so awesome and energizing and left others feeling the same way that you couldn't express the feeling enough?
Ask yourself are you happy where you're at right now? What are you doing to change it and make it better if you are not? Or even if you are happy what are you doing to make your life even better ? Are you striving for more? Pushing for more? Or are you settling? Everyday we choose to settle is another day we hold ourselves back from our true potential.
Keep those goals close my friends, write them everywhere. Review them daily and tell yourself it's possible to accomplish them and that you deserve it! Soon you will be there I know it!