My first advice is what my father told me when I went off to college "Illegitums Non-Carborundum" (pseudo-Latin for "Don't let the bastards grind you down").
Second, if this pattern has been going on for six years, you can't expect it to change on its own. So either a) keep repeating to yourself "my boss is a shmuck and his opinion doesn't really matter" while saying to your boss whatever he wants to hear or b) start immediately looking for another job and say to your boss "listen, this time I really mean it, we can't do this right in the time we have either increase the time or decrease the task and if you won't do either, don't blame me when it comes out as I am telling you it will. If he hears that and then blames you, quit. You might go through a rough patch finding a new job, but you'll thank yourself in the long run.