During a lecture how to be more attentive ?

Listen to what they say and jot down questions you have? Often it will lead you in a direction that will make the topic more appealing to you. If you can ask questions during the lecture than that will help as well but by thinking of questions it will make you focus more to hear them possibly address your question. If not, like I said, jot it down so you can research it later.
I hope this helps. Good Luck.

I have been there and it is not easy, really. There were small things which helped me to keep myself upto those hectic classes.

Sharing notes with friends.
Little ‘in house’ jokes and fun.
Texting my BF, in between.
Looking forward for the ‘Oh! so cute’ lecturers hour.
Trying to impress the strict Philosophy professor, which almost never happened.
Making sure I make note of the things I either missed or did not get.
Doing a quick check of the topic, on hand.
The most important of all the things was the much anticipated wait for me to go back home. **phew!**

It will be over, one day. Till then, hold on and smile, works, did for me. **wishes luck**

maybe youre in the wrong course, have you re-evaluated your interests lately? they do change. sometimes distractions outside of learning can have a detrimental effect to in which case you may need to have a talk with youself.

Coffee.

Stay hydrated, try chewing gum and sit on the first bench. I found out that when I sit on the first bench, its impossible to doze off!!

Sit up front, and suck on peppermints (they promote alertness)

If the lecturer is attractive to you, I suppose you might try imagining them naked.
Well, it would help focus your attention…..pointed in the right direction, but on the wrong subject (tho it might be a whole lot more interesting than the subject matter).
See ya….Gary/wtf

Since you are already taking notes, try to relate what the lecturer is saying to applications useful to you. If it’s something you are totally uninterested in just concentrate on the process of note-taking and trying to determine what portions of this will show up on an exam.

Actively think about what is being said. If you’re being a passive listener, of course you’ll get bored. Make connections, think about the implications, wonder about the details, think of how it ties into the big picture.

Try giving a shit might work

I personally pretend to have a conversation with the lecturer under my breath and occasionally question them aloud. I’m aware that would appear odd and..well..it does but the learning method that I have found works best for me (by a huge stretch) is discussing whatever it is that I am learning but unfortunately I would feel rude disrupting a class every few minutes because I have a question so instead I ask the questions to myself and attempt to speculate how the lecturer would retort.
My friends often joke about me hoping to become a Neuropsychologist yet appearing completely insane in lectures when mumbling to myself ;)
I hope you find a method that proves effective for you.