I was listening to an interview to Loch Kelly when he recommended this practice. I remained focused on the heart space for about 90 minutes (during the interview and afterwards). Unexpectedly, very pleasant sensations arised, as if the heart opened, lasting several days.
I tried to achieve the same positive results again, but unfortunately was not able to have a similar experience. I now believe the positive feelings were a consequence not only of shifting from head to heart, but also of practicing "deliberate mindfulness" and pranayama. I was doing lots of body scans per day, and stopping the breath (1 minute on the inhale and 30+ seconds during the exhale). In the past, I also used EFT tapping to experience feeling good, and practiced “Be Happy” (i.e., let the attention float between all positive and all rest).
If you're interested in trying the shift from head to heart, these are the instructions:
Unhook from thinking and have the awareness know directly your breath from your nostrils. Then, have your awareness drop and know your jaw directly from within your jaw and then, have your awareness drop and know your throat directly from within your throat.
Continue to drop below your neck into your heart space, and just feel as if you shifted down. Remain here. Now, you’re actually knowing and feeling from this open hearted, embodied, soft, and wise place.