Setting goals about how to feel can be good or bad. In this case, it's not a good thing. You are telling yourself you can fall below the 50% mark, but constantly keeping this in mind will only push you closer because you won't let yourself let go and feel how you feel (as much as it may hurt). Then when you do fall past that point, you will feel crummy and be angry and punish yourself for not meeting your "goal." You CAN fall below that point; it is possible. You will TRY not to. But if you do, it's okay. You will eventually find a way back up, especially if you can manage to hold on to the good moments, the moments when you feel free. Write as much as you can if it keeps you floating.

You asked yourself how long before you give up again. If you phrase it that way, you are setting up your own demise ahead of time. True, you are familiar with that and wouldn't be disappointed if you expected it. But you also have no chance at something better, at feeling happier if you don't take a leap of faith that maybe "giving up" is not the only option. Where you are now is not a fun place. You got there by giving up. If you continue to give up, you WILL stay in the same place. Perhaps it's time to try something different.