I've noticed I tend to have more faith in other people's convictions than my own, assuming, essentially, if they believe in something, there must be a great reason behind it
My own opinions tend to be weakly expressed & weakly held. It's usually been good, allowing me to listen and understand others. However, growing in career, I feel my opinions not taken as seriously because the perception of their weakness.
What I've tried, maybe the reverse of it might be helpful:
1. Consciously reflecting that other people have roughly similar amount of self-doubt, even if they don't express it. Even if they present opinions strongly, it doesn't necessarily mean these are right.
2. Lowering the bar for going from 'this might possibly be..' to 'i think this is..' to 'this is..' --- that has been very uncomfortable, and still is depending on the audience.
I love working with peers who don't over-sell their opinions, but have adjusted to have a more equal playing field with those who are more opinionated (both kinds are great people).
+1 to the mention of curiousity elsewhere in the thread - realizing there are many ways to look at anything, all 'right' to some definition of the word based on the person's background and context, can be quite liberating, a fight for being right becomes a journey to understand better how people work.
My 2c, not strong opinions :)