The biggest reason why most will not change is because most people are being influenced by bad people. Some are raised in bad environments others are influenced by the people they surround themselves with. But ever person that lives on the Earth is mainly influenced by the devil. It is his job to do what ever it takes to keep people from being closer to God. Once people realize that devil is the enemy and he is doing what ever it takes to make them do the wrong or sin , then those who fear God will change. So if you are a drug addict; alcoholic; over weight and need to exercise; on prescription medicine and refuse to take your medicine; having a affair with a married person or doing anything that you know is wrong, then you need to change. I know you don't want to, but you really need to change. God loves you and he really wants the best for his people. As Gods people we all must realize that we only have one life to live, one body and while we live plenty of chances to get it right. So while we have breath in our body, do what most don't want to and change your life. Do what you need to and become one of Gods children.
Have a blessed day,
Timothy 3:2 For men will be lovers of self, lovers of money, uplifted in pride, given to bitter words, going against the authority of their fathers, never giving praise, having no religion,
James 4:6 But he gives more grace. So that the Writings say, God is against the men of pride, but he gives grace to those who make themselves low before him.