raise/lower your sights
lower one's sights
Fig. to set one's goals lower. (Alludes to pointing the barrel of a rifle lower to lower the aim of the rifle.) Even though you get frustrated, don't lower your sights. I shouldn't lower my sights. If I work hard, I can do what I want.
raise one's sights
Fig. to set higher goals for oneself. (Alludes to someone lifting the sights of a gun in order to fire farther.) When you're young, you tend to raise your sights too high. On the other hand, some people need to raise their sights.