Question

highlight the word or phrase that makes the thesis statement wordy. community members that learn to control their feelings are happier and more productive, in my opinion.

Explanation:

The phrase "in my opinion" is unnecessary and makes the thesis statement wordy because a thesis statement should present a claim rather than explicitly stating it is an opinion (unless the opinion aspect is crucial, which it isn't here for a concise thesis). Removing it would make the statement more direct and concise.

Answer:

in my opinion