There are three kinds of students. Passive students, active students, and any between, though in reality we all sit somewhere between.
Being a passive student is not always bad. The more interested you are in a subject the more passive you can be, as you will absorb more when you are interested. By being active on all subject matters, you may increase your workload. If your teachers say that something is not important, it probably is not, and here is where it pays to be passive and not rack your brains on these matters. Of course those are only a couple times when being passive is okay, the rest of the time you should be active.
Being a passive student will only get you so far in your university career. However, to become active you must want to be. It is not a simple transition but if you are passive at university, you will soon learn this will not get you far. There are many things you can do to make learning easier, if you find ones that work for you, you should stick with them. You should also not be afraid to try new learning techniques.
Many university lecturers will post outlines or lecture slides online for you to view before attending a lecture. If you print these off and read them before your lecture, you can pay selective attention to examples given outside of the notes. Where notes are not given out, you should learn to spot what is important. Effective lecturers will pause, give examples and repeat ideas to establish main points.
Most lecturers are also willing to communicate outside of lecture times. If you are ever not clear on subject matter, make use of this by asking them questions to gain a better understanding.
Learning is something that rarely is effective just inside the classroom/lecture theatres. To truly learn you should put in extra time at home, or if you get distracted at home make use of a local or school library. Reading extra books on subjects will often clear up any confusion because they will often use different explanations or examples. Books may also be more interesting on subjects you found boring.
One of the major things in becoming an active learner is lifestyle. If you are constantly tired, you will be stuck in passively watching information pass by. Sleep and nutrition are essential in keeping you aware. Awareness is the key to learning. Activeness is awareness.