Even after doing many times, it is still not easy to submit, resubmit, revise papers. Interestingly, difficulty is higher when the work is not very strong. Strength or novelty of the work is almost all determined from idea proposal stage, and typically not much change or affected whatever done afterward.
Until yet, I typically just push out even when I feel not very excited about the idea as long as it is not too bad - which inevitably incured shortage of my time and frequently invited unnecessary collaboration to decrease my time investment burden. I nowadays learn that this is a bad strategy. It is better not to spend time on so-so ideas and fully focus on only good things without inviting unnecessary additional labor force. Also, inviting too many people to share work sometimes sends wrong signals and confusions, which is hard to correct later without serious measures.
Maybe this is because of academia's nasty nature. It is easy to criticize others while it is hard to propose something great. Also, it is easy to overlook other people's greatness while overvaluing one's own things.