However.. I think there may be an opportunity for personal growth here. Though it's probably too late to fix this situation, you can be prepared for the next time.
Put yourself in his shoes. He wouldn't do this for no reason. What makes him think you aren't working hard enough? What do you think are his main issues with your specific behaviors and actions?
Are you failing to show the results of your labor? Are you busting your balls on 80% of the problem, but never closing out that last 20%, making it look like you never did anything?
It's important that your boss understands your role in detail, your accomplishments in full (soon after they happen), and your value to the company.
What is getting lost between your effort and his comprehension of that effort?