In our modern, more secular world, words such as "sin" are to be avoided, and words such as "weakness" when applied to our choices, are often excused. Instead, we are led to the false belief, that what we are is what we are, human frailties, unfair circumstances, peer pressure, dysfunctional families, and that we shouldn't have to take full responsibility for our actions in life, but this type of thinking is fundamentally wrong and fundamentally flawed.
Each of us is most definitely responsible for our own lives, for we are all individuals, gifted with free will and free choice, no matter what the circumstances are that we face, it therefore is up to each one of us, to make our best choices day by day. Those choices that we do make do define us as human beings, and always those choices and decisions are within our hands, so the determinate as to whether those choices are indeed the right ones or not, separate those that have strong will from those that do not.
The temptations that we face each day are ours to conquer, to boss, or to concede to, in which, many people give in to temptations that they know explicitly and implicitly are wrong, but they want to indulge themselves for whatever reason, of which most of those reasons stem from weakness of the mind, or weakness of the body, or weakness of the spirit. So often there is this basic incorrect thought, which says "just this one time", but every time that you give into that thought, that weakness grows stronger within you.
It's a mistake to say to yourself, that "I will just go with the flow", for dead bodies and objects have no choice but to go with the flow, because they have no strength to do anything else but that, whereas, human beings have both strength of mind and strength of spirit, to fight against the flow, if they so choose to do so.
The defeat etched into so many faces, comes not from not trying, but comes rather from trying not, and instead giving in to things that they know are morally wrong, foundationally wrong, and have no good purpose in it, yet believing somehow, that what they have done will not have a material impact upon their life, but God is not mocked, as there are no shortcuts to His throne, for all that cheat here on earth, have cheated themselves from Heaven.
You cannot sin in this world, except from weakness, as always the choice of what you do or say at any particular moment, is yours to make, correctly or not. If, for example, you don't like some of the things that you do, stop doing them, for if you don't stop yourself, it will just keep reoccurring. The reason that we have so much repetition in life is for the very purpose, of correcting or confirming our behavior, for things not corrected, will repeat ad nauseam, until they actually are corrected.
The weakness and the troubles that we complain about, are there to remind us, that we have room to grow, room to improve ourselves, and trials to overcome, all made easier, if we demonstrate the strength in character to do so, knowing always, that God is our bedrock to lean upon, and our very present help in trouble.