There are two kinds of big decisions to learn to watch for in one's life:
Those that have more or less obvious long-term consequences (basic career choices, choice of mate, choice of values, choice of philosophy, basic parental decisions);
Those whose long-term consequences must be "discovered" (such as the implications of our daily habits, including those implicit in our eating and exercise habits).
What is most dangerous in general are "un-thought" decisions, the decisions that creep into our lives unnoticed and unevaluated. Clearly, it is not possible to raise all decisions to the level of conscious realization, for then we would have no habits whatsoever. Rather, we aim to evaluate categories or clusters of decisions, on the one hand (big in their collectivity), and the individual big ones.