If you feel tense, you need to relax first, and then start to be aware again.
You need to learn how to be aware in a relaxed way.
The important thing is the continuity of awareness. If you’re tense, be relaxed and start to be aware again. Slowly, the mind will understand how to be aware in a relaxed way.
Now, you need to learn how to be relaxed and maintain the awareness – that’s enough. Investigating or watching the mind – you only do that later.