Saving The Impossible Goal

My 2018 Impossible Goal was to write 4 novellas, one at each quarter.
We are in June and I have done very basic outline of two of them and what I noticed now is that I kept getting excited over a novella idea and then finding a new idea that seemed better and so for six months I have been unconsciously avoiding seeing an idea all the way through in disguise of ‘Hey, this idea actually seems better!’

So it’s good that I am finally onto myself and realized that it’s a subtle way of my brain to protect me from actually going for an idea that might turn out later to be not as good.

My question is should I press myself on getting those 4 novellas written in half a year that is left or should I give up 2 of them due to half the year is gone?