Sometimes, you'll have to say no: No, I can't do it; no, it can't be made in this time; no, I don't feel capable of doing this; no, I don't feel comfortable writing this.
Saying no doesn't mean you won't do it. Once I had to say to our CTO: "Ok, I'll do it, but I want to note that I don't agree with what we are doing." In the end, the app was barred exactly because the thing we were doing.
Being explicit about what you don't feel is a good point may not be what some higher ups are expecting. The fact that you don't approve but will do it anyway may be something that can either show that your not simply a drone or, unfortunately, label you as a "troublemaker". Honestly, if you feel it threw you in the former, you should start looking for a new place to work. If you said you won't be comfortable and still did the work, and they had to label you something, then this place doesn't respect you as a person.