I USED TO BE...
I used to be a horrible basketball player, but now I'm a much better player.
I used to be a slow, un-paced runner, but now I am a much more faster, paced runner.
I used to be a wild, loud kid, but now I'm more mature and calm.
I used to be very lazy and un-determined, but now I'm more hard-working.
I used to act stupidly, but now I think more.