The Lord placed into the salmon a 'heart' after the place of its origin. If nothing interferes, it will unfailingly return to its birthplace. I do not say it is easy for the salmon to do this. On the contrary, it must employ all its faculties to achieve what its instinct directs. The 'heart' or instinct given into the fish is everything needed to succeed - but not without everything in the salmon in the swim.
Should we remove all interference - the lust of the eye, the pride of life, the love of self and the world - our new hearts will inspire us to run relentlessly to the Source of our life just as it was made to do. As with the salmon, the attainment of this call will require the full engagement of our will, desire, and energy.
God, Himself, would then say of such a servant:
'Behold, here indeed is a man after my own heart.'