Looking at the negative, seeing the glass as half empty, and complaining are the absolute biggest wastes of time a human being can engage in. I highly recommend, whether it is through therapy or just kicking the habit, cut your complaining in half till you are no longer used to just doing it without thinking. Systematically. Post-it notes. Listening to positive podcasts. Doing mediation. Whatever helps you do less complaining. It truly is one of the biggest things that can stand in the way of success, both professionally and personally. I would be remiss not to have it on this list.