Knowing the challenges and obstacles you face is necessary for preparing yourself to face them. With that in mind, what are your vices?
While the classic seven deadly sins — greed, envy, sloth, pride, gluttony, lust, and wrath — are a good place to start in considering potential vices, it is far from an exhaustive list.
And it is not even clear that they are all vices. Why shouldn’t I be proud, say, of a hard-won accomplishment? And just what is sloth, anyway?
This is not, however, to discount from legitimate vices. There are certain behaviors and habits that can be quite destructive in any number of ways. If you find you can’t resist some habitual behavior — playing video games at the expense of everything else, for example, or drinking to excess, or gambling money you can’t afford to lose — that could be the sign of a problem.
With some amount of introspection, you can probably think of some parts of your life that you wish you could change. It might be as simple as being habitually late, or as complex as addictive behavior.
One thing to avoid, however, is letting others define your vices for you. What someone else thinks of as a vice might turn out to be a virtue for you, in the end. If you feel strongly that something is right for you even though others disagree, it may not, indeed, be a real vice.
In the end, it is important to understand and be realistic about yourself, including both your good and bad points. Knowing certain activities lead you to bad decisions can help you avoid those activities. It might be uncomfortable, at times, but probing and defining your own weaknesses can ultimately make you stronger.
Related questions: What is your weakness? When is it useful to fail? What do you do that you shouldn’t? What is uncomfortable but rewarding?