Everything has a reason, even our fundamental core values can be derived onto one singular constant.
For example, You may want a family, because they provide you with understanding, security and affection; feelings and emotions without which your action couldn’t be internally justified, and without internal justification you cannot exist. That’s the basic component of continued consciousness. There are actions which cause your family to be dissatisfied or even dismantled. And there are actions how high will lead to strengthening your bond with your family. This is what your moral compass will be constructed upon, actions which bring you closer or drive you from your instrument for internal justification.
You may want a fulfilling job, that provides stability, depending on the work a fix or flexible routine, co-workers, goals, repetition or spontaneity, creating or destroying.
You may devote your life to religion. Finding a drive outside yourself, following someone else in hopes that they will reward you for your work.
Or you may want experience. Positive feelings and emotions are in themselves what you crave: love, excitement, happiness. You deem actions as positive if they help you achieve these values, but you don’t attach any further tier of logic to them, like a family, a job, justice, creation, preservation, destruction, etc. These positive experiences release happiness hormones in your brain without those values. They are beneficial to you no matter those variables, although some may call this hedonism, but what are others if not hedonists with more values.
Or you may be like me, partly, just slightly different from the last example, you may not distinguish between positive and negative emotions in your experiences. This is where I seem to break the Freudian pleasure principle. You may take whatever sorrow, guilt, hatred, pain, suffering may come at you and you embrace those feelings as you would do with affliction, love or hope. Granting that you may enjoy positive ones more than negatives, you still welcome both. I, for example, generally try to avoid physical pain, slightly because of the physical feeling itself, notably because actions leading to that kind of pain can be counterproductive. (e.g. meaning: I won’t intentionally look for a way to get shot, and if the situation arises I will try to avoid getting shot if it’s more beneficial to some temporary goal.) But I if I do get shot, I’ll seize the pain, experiencing everything around it, immersing myself into the gunshot.
Negative psychological emotions I grant more than physicals ones. Maybe even more than positive psychological ones.
This internal justification is mostly subconscious, it’s main actor is the ‘id‘. This constant is present in all life, although its’ complexity is heavily varied. Humans as the current apex of nature, have the deepest mechanisms in their heads, albeit some humans demonstrate capabilities hardly better than an ignorant animal.
One could most approximately define it as a constant need, an internal justification of one’s existence and life: a meaning.