The discussion was centered around the final two aspects of mindfulness of mental factors or ‘dhammanupassana’

The final two sections are on: (i) Seven Factors of Enlightenment (ii) Four Noble Truths.
 

Enlightenment factors’ role in removal of physical ailments -  Buddha and other enlightened disciples when struck with certain physical ailments reminded themselves of their development of these enlightenment factors.  Such recollections cure them of their painful illnesses.  These were recorded in Bojjanga Sutta’s in Tripitaka.

The Seven Enlightenment Factors are:

Mindfulness
Investigative analysis
Effort
Rapture
Tranquility
Concentration
Joy

How to develop mindfulness of the Seven Enlightenment Factors:

When there is a factor -> clearly comprehends that there is the factor
When there is no factor -> clearly comprehends there is no factor
When arising -> comprehends that arising of the non-arisen factor
When fulfilling -> comprehend fulfillment of the factor arisen

How to develop the seven factors

The seven factors are developed sequentially since mindfulness factor leads to investigative analysis and so on.

Anapanasati sutta (Majjima Nikaya) explains development of the seven factors:

"How bhikkus do the four foundations of mindfulness developed and cultivated, fulfill the seven enlightenment factors?
Bhikkhus, on whatever, occasion a bhikkhu abides contemplating the body as body, ardent, fully aware, and mindful, having put away covetousness and grief for the world – on that occasion unremitting mindfulness is established in him.  On whatever occasion unremitting mindfulness is established in a bhuikkhu  - on that occasion the mindfulness enlightenment factor is aroused in him, and he develops it and by development it becomes to fulfillment in him.

Abiding thus mindful he investigates and examines the state with wisdom and embarks upon a full inquiry into it. "

(ii) Four Noble Truths

Why are these called Truths - they are applicable to (holds true to) everyone, irrespective of race, color, strength, size.  Also these truths hold at any time period (from past, to present to future)

Why is there only four - These are the four ways to solve any problem.
In general:

Become aware of the problem
Find the cause(s) of the problem
Have some idea about the soulution sought
The way to find the solution

Why are they  called Noble: It is more than just the mundane, it leads to a supreme happiness

When developing mindfulness about these, a person clearly comprehends the occurrences of these dhammas.  For example, sees illness as the nature of unsatisfactoriness etc. 

Other points discussed

 The importance of development of mindfulness

Mindfulness - the unique way 

Buddha's statements about the length a person has to develop mindfulness (seven years or could be even as short as seven days - but need to be very diligant and always mindful)

Necessity for practice to develop the mindfulness well