motivating your partner

I've been working on improving my health and fitness for the last 10 months. I've lost 28 pounds and several inches and am up to running 2.5 miles. I have a goal to lose 26 more pounds, a few more inches, and to run, at the very least, my first 5k this year. My husband is so proud of me for reaching my goals and being in the best shape I've been in over the 8 years we've been together. He loves the new muscles I have and is envious of how far I can run. He jokes about how lucky he is because most wives don'tget in better shape after the wedding! Despite this, I can't get him to the gym. He doesn't have much weight to lose, maybe 10 pounds at the most, but he could definitely benefit from some cardiovascular improvement and muscle building. Any tips for motivating your partner?