I was just like you in my 20’s. Then one day when I was studying momentum I realised that this sudden change is difficult to persist for long. Then after few days the routine becomes even worse due to failure of this sudden change. So I started taking baby steps. I changed one easiest item and kept the same routine knowingly till this one change becomes part of my habit ie around 25 days. Then I pick next one in difficulty and so on. So by next new year all my habits got changed into a better one. How to know that it is even better one than I wanted to, is to do it fully aware, fully conscious during the act and divided the act into 10 small parts so that consciousness can be kept during whole process. That which is virtuous will improve and that which is sin for me start dropping on its own! You may refer to few of my posts for more.