The title above is an old saying that I'm reminded of this time of year, as some students are now stumbling toward either dropping out or flunking. Sometimes the problems are practical (finances, transportation), sometimes they come from being in too many classes (which can be solved by dropping out of one or more), but often they occur because the student is his or her own worst enemy. That is, the student has the brains and sufficient time (if managed properly) to succeed, but not the WILL.
One of the most disappointing things that can happen to a teacher is to lose students. However, a teacher can only provide suitable conditions for learning; no one can "make" someone learn in a democratic free society. So the teacher leads the student to the possibility of learning, but if the student won't do it, it won't happen.
Sometimes students just disappear, and sometimes I can see what's coming but no amount of talking or helping can make enough difference. The teacher cannot do the work for the student. Some of the students who lack the will come up with myriad excuses why they cannot do what they need to do, others just... don't do it.
In general there are three groups of students: those who do the required outside-of-class work on time, and usually do it well; those who don't do any required work, which almost guarantees failure; and a third in-between group, who may do some things and not others.
Roughly speaking, the first group also shows up to every class, the second group misses many classes, and the third in-between group is unpredictable in their attendance. (Remember, attendance is generally the best predictor of success in college classes.)
"The worst form of inequality is to try to make unequal things equal." -- Aristotle
"Always do right--this will gratify some and astonish the rest."Mark Twain
"A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away." Antoine de Saint-Exup'ery
"Not everything that can be counted counts, and not everything that counts can be counted." Albert Einstein
"Make everything as simple as possible, but not simpler." Albert Einstein