Most business travelers think about hitting the hotel gym, but a new American Express-GBTA Business Travel Sentiment report shows which travelers actually do.

The winning group? Millennials.

Among business travelers who work out regularly at home, millennials were the most committed to maintaining their fitness, according to the survey. Forty-six percent of millennials—representing travelers 18 to 34 years old—said they are more likely to work out during every trip or almost every trip.

GenXers, defined as travelers 35 to 54 years old, came in second place. Forty-one percent said they go to the gym on every trip or almost every trip.

Baby Boomers, those 55 years and older, came in third, with 38 percent voicing a commitment to their hotel-gym workouts.

Top Reason for Skipping Hotel Gym Workouts

Although health consciousness is fashionable, the fact remains that less than half of the leading group, millennials, spends time exercising while on the road.

The survey asked, “Why not?”

The No. 1 reason was time. Seventy-one percent of those surveyed said their schedules were simply too busy to work in a workout.

No. 2 was energy. Forty-seven percent said they were too tired to switch to exercise mode.

The third-most-cited reason for passing on exercise was the break in routine: Travelers said they couldn’t shift into a new exercise regimen.

Meanwhile, 17 percent provided the most valid excuse of all: no gym at the hotel.

But that doesn’t mean that travelers don’t want to work out. Sixty-three percent said that when choosing their business hotel, the availability of fitness facilities or places nearby to take a walk are deciding factors.

The Cure for Workout Guilt?

Another trend noted in the survey may indirectly have an effect on business travelers’ habits at the gym.

American Express-GBTA found that business travelers are booking more nights with home-sharing services such as Airbnb and HomeAway, with a 20 percent spike over the last six months.

And short-term rentals rarely come with gyms.