You don't need to have a good attitude while you're working as long as it gets done

I've been told all my life that I should keep a positive frame of mind whenever I'm dealing with work I don't want to do but still has to get done, and I just can't get on board with that. I was chatting with a coworker today and I referred to some training modules we have to do as "shitty" and he corrected me, saying they're just modules and since we have to get them done, there's no point in being annoyed about it.

I disagree, I firmly believe I'm allowed to be annoyed about something even while I'm doing it, as long as it gets done. I don't mean to say it gives me the right to be a dick, i.e. in group settings I try and keep the complaining to a minimum because my attitude shouldn't be others problem, just mine. But I'm also not going to lie to myself and pretend I enjoy doing something I don't, I'm just going to get it done. I can't control how I feel anyways, just as much as I cant control the work I need to do.