First Post! How to see a song through to the end

[Gordon Currie]

Kudos to the OP for recognizing a common pattern and desiring to change it for the better!

I've seen this in all kinds of artists (not just musicians). The most common outcome is dropping the activity after years of work, due to lack of progress or fulfillment.

Most of us seem to need to work at internal goal management when it comes to artistic/creative pursuits. There is a lack of established pathways to success in the arts.

For music, performing or studying with a teacher are common ways to find external factors that can help overcome natural tendencies to wallow.
Audiences don't like song fragments. Teachers lose patience when you haven't practiced the assignment.

Frankly, I do not consider anyone who cannot play a song from beginning to end a musician, just like a writer who cannot finish an article, or a painter who cannot finish a canvas.
They are possibly 'becoming' an artist, but they have not achieved the minimum yet.

My advice - make the 'finishing' part your #1 priority for awhile. This may be unpleasant and frustrating (especially at first) - so what? You're attempting to learn and do something that is quite difficult for many. Good luck!