1. I absolutely hate it when participants in a meeting use the phrase "I think.." or "I thought...".
2. This phrase is typically used by Sinkie educated employees who lack confidence. If my subordinate uses such sinkie phrases in a meeting that I am in, I will pull them aside after the meeting, lecture them about confidence when presenting an argument and the right way of convincing others about his or her point of view.
3. Use the phrase "I believe". It shows you have stronger principles and passion on the subject matter which you are dwelling on.