Don't change your mind later when you've already started something.Just Finish.

Its dangerous to change your mind once you've started something involved and difficult - stick with your choice, and don't ruin what you already have.

don't look back just keep going don't change horses in midstream

There are times when changing one's direction is OK, but there are also times when it isn't. Be careful of your surroundings and meanings and decide if a change is appropriate at this time. On a horseback ride, one can certainly change horses at will, and almost any part of the ride would do for it. There are certain parts of the ride that are particularly hazardous for changing horses. Mid-stream would be one of the worst times. Earlier would have been better, or even later, but during that one little part of the trek, the advantages of a fresh horse do not outweigh the risk of changing at that time. Stick with what you are doing during the hectic times. If you feel the need for a significant change, don't do it during a problem. Save the change for a quiet time. There would be more control of the situation and the change will be safer.