The past 4 months were a lesson learned. All of my projects fit perfectly on the calendar for the past year....except one thing was missing: rejuvenation and rest time. And I find people need different amounts of unplugging to feel like themselves again. The key is to catch it before it happens. I fortunately learned my lesson and was able to share with my team. I put boundaries in place. It's a new muscle and takes some time to learn what you can handle. It's really learning about your limits. It's about catching yourself before enthusiasm takes hold and we go on automatic pilot and sign-up for something we just can't handle at the moment. And I find this changes at different times in life as well depending on what else is going on. On a side note, I recently went through Todd Herman's 90 Day Year program. It was really helpful when implemented to help avoid burnout and know where your energy is best focused. It's looking at company data, checking in with yourself, seeing what you accomplish....It's a feedback mechanism.
You may have some depression lurking under the surface and the burnout might have been a catalyst or vise versa. I'd recommend talking to a therapist to have them help you work through what you're feeling and find the source of your problem. Once you get a hold on those reins, it will be easier to focus on what gave you drive initially, and what allowed you to work at a higher level of performance.