Just like your vehicle that could stop running on the highway, your mind and body can only tolerate being overworked so much. As entrepreneurs, we feel obligated and are inherently wired to work as hard as possible without looking back. This type of work ethic, although beneficial to achieving professional success, is far from healthy.
In the analogy above, the first thing you'd do to repair your broken vehicle is search for and purchase new truck batteries. It doesn't matter if you find deep cycle batteries or something that might not be a perfect fit. The most important thing is that it is being repaired. It is getting it's much needed rest before going out to the highway again for more hard work.
If there is a lesson to be learned here it's that your brain is a muscle. Just like in exercising, especially weight lifting, your muscles will not get any bigger or stronger during the workout itself. It's during the repair process that they rebuild with improvements. The best time to do this is through sleep throughout the night. If you treat your brain the same way, you won't risk being overexposed and overworked. Subsequently, you will also remain extremely excited about the work you do.
Remember, there's always tomorrow to accomplish more by becoming more productive during the necessary work hours.