Habit

I'm often repeated and hardly defeated Could be good, bad or ugly it all depends on what you make of me I run a full course when fully encrypted I am Habit I can make you soar sky high As well as fuel your eyes to cry Can lead you to great profit or lay you down underneath Its still me Habit A friend to both the achiever and mediocre The very small stream that makes a river What's your flavour? I make and mar Can keep you redundant or take you far Call me Habit Be firm with me and you'll achieve a great feat Be easy with me and you'll be wasted six feet