Getting individuals engaged and involved is a powerful way to make sure referrals keep flowing, and that can be especially true when it comes to groups.

Creative, fun, and highly motivating challenges can boost friendly competition and elevate your gym or club’s reputation as a place where goals are crushed.

Here are four fitness challenge ideas for group and corporate members:

1. Cross-country Marathon

If a group or corporate team is interested in cardio challenges, think of fun ways to represent mileage on treadmills, rowing machines, and ellipticals that go beyond simple numbers. For example, you could create a map that illustrates distance and put a “runner” figure on it representing a specific team. The groups compete to see which team can “run” the farthest—across the state, for instance, or through multiple states—with a predetermined endpoint.

2. Photo Treasure Hunt

Anything that makes adults feel like kids usually boosts participation. Get in the mindset with an old-fashioned treasure hunt that begins and ends at the gym and focuses on healthy “treasures.” For example, groups can be tasked with running to a local park and taking a photo of every team member trying to climb trees, or attempting cartwheels, with the pics tagged on Instagram. Once they’re all back at the gym, you can use a projector to stream the photos and award prizes. Bonus: This is a great boost for your social media, too.

3. Fitness Passports

If you’re looking to increase attendance for group fitness classes, create a challenge that’s tied to a specific timeframe and offer materials that track progress. For instance, you might create a “passport” that needs to be stamped by a group fitness instructor after class, and the team that gets the most stamps within a month wins. Match the prize to the challenge—for instance, a corporate group could win an on-site class from the instructor of its choice.

4. Play Up Weird Holidays

There are often challenges related to common holidays or times of year—like a Thanksgiving weight-maintenance challenge or a summer shape-up promotion. But you can also have fun with targeting the obscure holidays. For example, February 22nd is Walking the Dog Day, which can be done with an actual dog or as a yo-yo trick. May 4th is Star Wars Day (as in “May the 4th be with you”). Offer rewards or promotions to whichever team can best embody the spirit of the “holiday.” Another idea is to create your own fitness-related holidays and make them fun. Think about something like National Wall Sit Day or International Plank Pose Day.

No matter what fitness challenge ideas you choose, be sure to track participation levels and ask for feedback so that you can tweak (or overhaul) a challenge the next time it’s brought around. Challenges are much like individual fitness goals: They work best if they’re revised based on insights and data and you have a clear aim in mind when it comes to results.