You need lots of practice trying to be aware of thoughts; and also some understanding that thoughts are happening in the mind door.
Every time the mind thinks, just know, just know, and try to know. You need to learn how to be aware when thinking is happening. For example, we try to be aware when we walk. It’s the same with watching thoughts.
Awareness is not forcing to be aware – awareness must be natural. Natural awareness can do this (notice thought and awareness at the same time); if you put in personal effort, it cannot be done.
Because we’re developing natural awareness, we need to continue to be aware in a light way for a long time until it becomes a habit – it starts with trying to be aware whenever the mind thinks. It’ll take months and years of practice.