Back in high school, I learned the proper answer to, "How is life like this cup?" I heard that question more than you would expect, certainly more than makes sense to me looking back on it. It would always be posed by someone interviewing me for some award or position or scholarship. The asker usually sat across a desk or table from me, and they would hold out a cheap paper cup as they watched my reaction.
The proper reaction, I soon learned, was to take the cup into my hands delicately, as if it were a prehistoric figurine of brittle clay. Then I would scrunch my eyes together for a bare second and scrutinize the cup, before responding slowly, "This cup is like life, because you can only get out of it what you put into it . . ."
Treating life like a cup--because you only get out of it what you put into it!--shouldn't be taken as some sophisticated or deep life philosophy. The analogy, at least as I learned it, was juvenile in more ways than my age; I deployed the comparison more to convince authority figures to give me things than as a sincere expression of my approach to life.
It's still true, though.
Decades later, when I put in sincerity, effort, and thoughtfulness, I get paid in turn. When I put in bitterness, discontent, and disregard, the results I drink are not as sweet. Trite or not, I prefer to fill my cup with what I want to get out of life.