Keep One's Eye On The Ball Meaning

(idiomatic) To maintain one's concentration fixed on one important theme.

Example: 2006 Feb 18, Michael Holden quoting Sir Alan Sugar in The Guardian, You can call me Sir Al
  My ethos has always been to be very straight with people, tell it as it is. It doesn't often make people happy but I found that over a period of time it's better to be that way. So being straight, also being very focused on your objectives, keep your eye on the ball and not get deflected away from it.