「Tongue, tonguing」with「breathe」perhaps to mean one's tongue is hanging out as you pant like a dog and you need a BRIEF REST, to TAKE A BREAK, a short RECESS from whatever you are doing, an INTERMISSION before continuing.
　「Using one's tongue skillfully with one's own spewing penis」such as while attempting to perform autofellation will invariably result in the NEED TO RELAX AND TAKE A SHORT REST from those endeavors before continuing (try it yourself, you'll see).
　And as was common in older cultures of human beings, such as the Sambia Tribe of Papua New Guinea still today and also the Marind-anim, Kimam, Bedamini, Etoro, Anga, Gebusi, Baruya, Kaluli, Jaquai, Kiwai, Onabasulu, and Elema, what you may well have been doing is depicted by the upper left element,「repeatedly bobbing your head while tonguing」which is likely an activity during which breathing may be difficult at times, and that would require you to cease using your tongue and mouth in order to breathe a bit, a RESPITE, RECESS, MOVE BACK from what you are engaged in doing for a short spell, step back from what is「directly in front of one's eyes」to「take a breather」or have a brief rest. Note that the glyph meaning「breathe」is also the same glyph meaning「son, gasps, penis, pushing down on the back of someone's head」and the above-mentioned cultures still today practice the oral insemination of one's own「tonguing sons」in order to provide them with additional testosterone, a valued and highly sought steroid especially by professional athletes to build powerful muscles and a sharp mind, and this may give a hint as to whose duty it was to perform the「daily tonguing」(活) in early human societies (for his own good, of course, of course…)「tonguing for one's own spewing penis.」
　Nevertheless, literally as「tonguing, eating」「one's own spewing penis」or the English expression translated literally from these Chinese elements and brought back to England centuries ago:「eat your heart out」seems to be a rather crude suggestion to autofellate if possible: 'do that, if you can, see how good I am at doing the impossible and can you do the same?' or pointing out someone else's suffering from an excessive longing, especially for someone or something unattainable (unlike dogs, not many male humans can actually autofellate, since that allele has been very nearly eliminated from the human gene pool due to natural selection, but that fact hasn't prevented most boys from the attempt to do so). Also, suggesting to「sit down and take a rest while watching how this is performed by someone who can do it well」such as by one's「tonguing son, repeated head bobbing on the old man.」…now that's true father-son training and filial piety to the utmost as taught in dynastic China, it seems.

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: to rest
Japanese: rest, to, to relax, to repose
Unihan extended: rest, take rest
EDRDG: recess; rest; relax; repose