[BigV]

I am your constant companion.
I am your greatest helper or your heaviest burden.
I will push you onward or drag you down to failure.
I am completely at your command.

Half the things you do, you might just as well turn over to me,
And I will be able to do them quickly and correctly.
I am easily managed; you must merely be firm with me.
Show me exactly how you want something done,
And after a few lessons I will do it automatically.

I am the servant of all great men.
And, alas, of all failures as well.
Those who are great, I have made great.
Those who are failures, I have made failures.

I am not a machine, though I work with all the precision of a machine.
Plus, the intelligence of a man.
You may run me for profit, or run me for ruin;
It makes no difference to me.

Take me, train me, be firm with me
And I will put the world at your feet.
Be easy with me, and I will destroy you.

Who am I?

I am HABIT!