Snacks, hydration, and stretching help a lot. I play better when I walk around every hour. Also, I avoid multitasking—once missed a great hand because I was texting. Big regret.
I keep snacks and water nearby, take quick stretch breaks between hands, and use blue light glasses to reduce eye strain. Also, I use Spinio https://spinio.ai/chat to simulate scenarios and sharpen my decision-making during downtime. It helps me think a few moves ahead and stay mentally engaged. Also, keeping a calm playlist in the background works wonders.