External clues are better than internal clues

I read a lot of books these days in order to close a huge gap. It's the 'how' to learn something not the 'what' to learn that interests me these days.

Many sportive people have a coach, who motivate the sportswoman. What is said in such a session can be effective or less effective.

If there is no coach or teacher, there is self-talk. This can be motivating or not. It can be effective or less effective.

One found out that external clues are more helpful than internal clues. An example, please have a look at the picture. 'Open your chest' is less useful than 'bring your chest to the wall'. 

(I know, the holy practitioners among us even prefer to think: open your heart.)

This is the work one can do. What is the external clue that helps me to get deeper into an asana?

The picture here is only 3 hours old. I practiced. It was not the early morning when I stood on my mat ready for the sun salutations. Too late I woke up and even with back pain. This is no longer an excuse. Back bending feels good, It helps to eliminate the pain. Amazing, but it is so.

After back bending I stopped my practice. It was enough.