Besides how long and what’s the ideal time to meditate, another question that often arises in the mind of someone new to meditation is what to think about during meditation. Regarding this question, several experts have shared their opinions.
Think About Nothing While Maintaining Consciousness
Several experts, including Naiwen Hu and Gwo-Bin Wu, recommended thinking about nothing during meditation. However, while your mind is empty, you should still keep your consciousness and self-awareness in the process, and very importantly, avoid falling asleep. 
Hu, an internationally renowned traditional Chinese medicine doctor, has studied several different practices involving meditation in the past. “All the practices that I have studied require you to not think about anything during meditation,” he said. …