'I'm adjusting my horizon' = I'm modifying my plans

Horizon (when we are talking about people) has two meanings 1 - the person's group of past expereinces and perspective "My horizon has been limited to the Arts." 2 - something that you wish to attain or achieve "Right now, becoming a doctor is highest on my horizon." Adjusting my horizon means that you are changing what you wish to become or attain. It can also mean that you are changing your overall view or perspective on something due to newly received information. Finally, the horizon is the visual "line" that separates the earth and the sky. So when you look out as far as you can, the horizon is where you "perceive" that the earth stops and the sky begins. Pilots have an instrument on the control panel of their planes that is called the horizon. Their aim is to keep the horizon level as often as possible, because that means they are flying straight. When the line is not level, they try to "adjust their horizon" to make it level. It is how they recover from a spin in flight.