'Doing' heart-thinking is not the point; we are all doing it, all of the time. The task is not to do it, but first to become conscious of it; and then to follow its dictates.
In childhood (and earlier phases of human history, apparently) many/most people lived in accordance with heart-thinking - but did so without awareness, and automatically.
Now, on the other side of our spiritual adolescence, we have lost the capacity (and now, in 2020, even the opportunity) for such spontaneous, natural life; and our choice now is whether to return to heart-thinking as a conscious decision, and to follow the dictates of the heart (which are aligned-with God's creation).
Or, in contrast, the choice may be to continue with the socially-prevalent (and dominant) alternations between bureaucratic pseudo-rationalistic materialism ('Ahrimanic' evil) and selfish instinctive hedonism ('Luciferic' evil). This (here-and-now) reliably leads to the choice of damnation.
Heart-thinking is the first goal of 'meditation', or prayer: to become aware of our own heart-thinking; which means to make matters so that our heart-thinking is in our conscious stream of thoughts.
Heart-thinking is always there, always going-on - the task is to bring it to awareness - to locate it among distractions, clear a path, encourage emergence... to notice and take-seriously our heart-thinking. (Because the purity of heart-thinking is an ideal, it is the divine within us; and as such in harmony with God.)*
To know and live-by heart-thinking does not happen spontaneously, but by decision. And we are not compelled to live-by heart-thinking; but must make a discernment to do so.
It is the role of head-thinking to fit that ideal to daily practicalities and constraints; and in this job we have (if we choose to access it) the universal spirit that is the Holy Ghost to inform and guide us, and provide encouragement.
And, although the above seems abstract - the reality is personal. The thinking of the heart is our real inner person - as opposed to our superficial (and typically fake, dishonest, manipulative or pathological) 'personality'. The Holy Ghost is a person. Our living in the world is a matter of living in relationship with Beings.
Living is ideally a matter of harmony with ongoing creation; which is a personal and purposive product of God's intention.
Our modern task (which extremely few have recognised, fewer still attempted) is (put simply) to do consciously and by choice that which was once done unconsciously and spontaneously; that is, freely and from personal agency, to do what was once done from lack of individual capacity and alternative possibilities.
We have greater capacities and more possibilities; and must choose The Right from among them - this is what requires to be done If, we wish to have eternal resurrected life in Heaven.
If Not; we can simply carry on as the mass majority do at present.
*Note: This means that our awareness of heart-thinking comes after the heart-thinking itself. The heart-thinking has already happened by the time we are aware of it. Consciousness tells us what heart-thinking has decided. A consequence is that heart-thinking comes temporally before consciousness; and consciousness - logical reasoning, factual information and the like - does not necessarily have any influence on heart-thinking, and any later influence consciousness does have, will be due to the 'internal' imperatives of heart-thinking.
Further added: To take-up a metaphor of William Arkle, heart-thinking is rather like trying to tune an analog radio to get a particular and previously-undiscovered channel. First we must know-about that 'real' channel, and want to find the signal. Then we may need to maximise reception by finding the best direction to point the arial, and exclude adjacent sources of 'noise': sparks, crackle, hum etc. This corresponds to spiritual guidance (where to look) and meditation (reducing distraction). Then comes the actual tuning, i.e. the precise twiddling of the dial and listening to discover... what? Well, we need to know the real channel when we find it among all the wrong and perhaps misleading channels; which entails both an inner recognition and an external confirmation of the validity of that recognition (recognition by the divine within us by virtue of being God's children; and confirmation from the universal divine outside us: ie. the Holy Ghost). This stage braodly corresponds with prayer. Finally we must choose to attend to the real channel, regard it seriously, and take note of its content in our lives.