ASPIRATION
buck for something
to aim, try, or strike for a goal. (Originally referred to trying to get a higher military rank.)Bill acts that way because he's bucking for corporal.Tom is bucking for a larger office.
raise one's sights
to set higher goals for oneself.When you're young, you tend to raise your sights too high.On the other hand, some people need to raise their sights.
reach for the sky
to aspire to something; to set one's goals high.It's a good idea to set high goals, but there is no point in reaching for the sky.Go ahead, you can do it! Reach for the sky!