I smoked a half pack a day when I started and did well as a 4/5. Podiumed, always top ten, a won a few. But, for me I could only get so fast. Quitting was a struggle but getting repeatedly stomped as a 3 I knew I had to stop. And a year later I was much faster and could hold a high pace for much longer. You'll never reach your potential and you throw a lot of hard work out the window