Think of it as a journey rather than a destination ;) Depending on how pedantic you are, you may never be finished learning a language - the beauty of it is that you can keep delving deeper and deeper! It will never get old. Even when I'm 80 or 90 I will be learning new things about my languages because they are always changing, they are living languages.
It can be very discouraging when it takes a long time (I'm looking at you, Arabic!) but just set small goals and keep reaching them. As if you were climbing a mountain - instead of always looking up to the peak 3000m above you, look around you on the path and enjoy the beauty of the landscape, lie under a tree for a while, and then keep going! By the time you get to the top you will have had a lot more fun than if you are always just pushing on looking up.