How do you structure training to maximize performance without burning out?

I am a older 48 M and I'm trying to figure out how to structure my week so I can maximize my volleyball training while avoiding exhaustion.

I play volleyball about 5 days a week, and I thought I could add 30 minutes of volleyball-specific running/drills plus 30 minutes of gym training on top of that.

The problem is that some days I become completely exhausted. Even after a good night's sleep, I may wake up feeling like I'm only at 60% energy and need one or two 20–30 minute naps to feel closer to normal. Sometimes I still don't feel fully recovered when I work out.

I'm trying to figure out the best balance of training volume, intensity, and recovery. Is this something experienced athletes generally figure out through trial and error and monitoring their own recovery, or are there specific coaches, books, training programs, or principles that can help someone learn how to structure their training schedule properly?

My goal isn't to train less—I want to maximize my training and improve while minimizing exhaustion. How would you approach this?