Personally if I come across as bored or unfocussed in a class or lecture it's because I'm thinking about another topic CS or otherwise that actually interests me.
Computer Science is such a massive all encompassing field and the way Universities and Colleges structure it is to try to turn you into some kind of Jack of All Trades.
For instance. I don't give a shit about Web Development. I hate it. I hated every single second of every lecture and every class I had to take in relation to it. I'm far more interested in Data Structures, Artificial Intelligence and Data Science topics, so that's where my mind tends to dwell. I feel like I wasted hours of my life learning HTML, CSS, Bootstrap, JavaScript, AJAX, JQuery, AngularJS, d3JS, C#, MVC, MVVM etc. and I don't use any of it and I don't plan to ever use any of it ever again.
There's endless templates and SAAS businesses out there that can allow you to make a beautiful looking website with minimal effort these days. Web development is a depressing industry as far as I'm concerned. The people who are in it are just constantly mopping up an endless shower of shit.
Everything changes and breaks every 5 minutes. It's definitely not for me, but still I had to get through a whole semester of it so I can get a nice peice of paper with my name on it at the end of this shit show.
That being said I know some people enjoy it and all the more power to them for it. But that's just my two cents.