Don’t be afraid to ask past colleagues (be wary of asking current colleagues, of course), family, friends, and those you volunteer with about what you have done in your various jobs (including volunteer work) that might be great to mention on a resume. What have you been really excited about that you have discussed regarding work? What projects do they remember you working on specifically? Do they remember you winning any awards or recognition's? What about a performance review that was particularly good? Do they remember you writing any standout documentation (manuals, policies, tips sheets, website verbiage, etc.)? Do they recall you training others in the workplace or giving presentations at work or in a volunteer capacity?
It can very difficult for us to see our accomplishments. Often the things we do daily are some of the most important information to include on a resume, but we just see it as part of our job. Getting another perspective regarding your career and your performance in various jobs can really help bolster the information you can provide on a resume. To your job search success!