Everyone experiences ups and downs. In business this is just part of the process. The way to get to the ups is really simple: just keep moving forward and focus on the goal. I know this may sound simple but that isn't the point. The point is to get to the end, the goal, that pot of gold and the way there is to just focus.
Focus means concentrating of what is necessary to cut through problems and then to act on these things. Some folks just bemoan the difficulties and therefore never get beyond them. In my experience the sooner and better you get at moving forward the better your chances are to resolve the issues and get to the solution. Focus on the goal.