I don't know much about your physical state. So, let me just put out some generic advice.
1. Enough quality sleep. 2. Exercises that involves your legs. Somehow leg muscles help the heart to pump the blood back up, keep enough pressure and circulation in your brain.
I'm 35 and I've already experienced the benefit of those 2 and the negative impact of lack of those 2.
Maybe you could be just rusty about that kind of code?