'Your trunk is smaller, mine has got bigger!' Jenna Bush Hager hits the gym with sister Barbara - poking fun at her 'jiggles' while praising her twin's 'ripped' physique 

Jenna Bush Hager has already given up on her New Year's resolution to work out more - but that may because she tried too much, too soon by hitting the gym with her super-fit twin sister and Today show co-star.

The 34-year-old shared two of her ambitious work-out attempts on the Today show this morning, taking cameras along while she worked up a sweat with Barbara Bush and Natalie Morales, 43.

But while she clearly had fun - and goofed off quite a bit - the exhausted mother of two proclaimed post-work-out their her resolution is gone, saying: 'We ended it today.' 

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Workout buddies: Jenna Bush Hager (right) hit the gym with her twin sister Barbara (left) in an effort to keep her New Year's resolution to get in shape

Competition: While Jenna pushes herself to the limit, Barbara, who seems to work out regularly, hardly seems to break a sweat

Look at those guns! Jenna also playfully compares her lack of muscle to Barbara's toned arms

'One of my New Year's resolutions was to get in shape, and the other was to spend more time with my friends,' Jenna explained.

Her best friend is her twin sister Barbara, so she invited her on a fitness date at New York City's Orangetheory fitness. The gym encourages patrons to get their heart rates into the 'orange zone', a range where they most efficiently burn fat.

That made it easy for Jenna to compare herself to Barbara, pointing out that her older sister - by one minute - is 'ripped', and clearly works out more often that she does.

And it showed, when they hit the machines. While Barbara barely seemed to break a sweat on the treadmill, Barbara comically freaked out as the machine sped up, asking frantically: 'Why's it going faster?'  

Jenna continued to struggle to keep her heart rate up, while her sister seemed like a pro. 

Hot gym: The duo work out at Orangetheory fitness, which focuses on getting heart rate into the optimal zone

Come on! Barbara encourages Jenna to keep at it, even when the older sister - by just one minute - is worn out

Changing bodies: Barbara points out, though, that Jenna has had two kids, so she should cut herself some slack

Let's eat! Jenna concludes that she prefers to go on dinner dates over gym dates with her sister

'Keep up your pace, yo,' Barbara tells her. 

Though the tough work-out didn't seem like Jenna's cup of tea, she did keep her spirits up, cracking jokes that she was having 'so much fun' as she panted. 

Together, they also try rowing machines and crunches, prompting Jenna to say: 'I prefer dinner dates.'

She also urged Barbara to show off her muscles while she made fun of her own 'jiggle', though Barbara was willing to cut her some slack.  

'Your trunk has seem to have gotten smaller while my trunk is getting bigger,' Jenna told her twin, while Barbara responded: 'Well you've had some babies in your trunk.'

While that's not quite anatomically correct, her point was clear - but it didn't seem to keep Jenna on track. 

Compliments: Jenna also works out with Natalie Morales, whom she calls ''one of the fittest friends I have'

Teamwork: They go to a Crunch Fitness in New Jersey, where they do partner workouts together

No comparisons, please! Jenna jokes around the whole time, noting that she doesn't want to go 'spandex for spandex' with her co-worker

Jenna also turned to Natalie Morales - 'one of the fittest friends I have' - for some motivation, joining her at a New Jersey location of Crunch fitness to exercise.

Natalie invited her to work out with her friends, whom she called the 'Hoboken Hot Mamas', agreeing to take Texan under her wing.

Jenna seemed a bit intimidated at first, noting that the Today show producers like to put her 'spandex for spandex' next to Natalie, but she rather not open herself up to that comparison because 'Natalie wins!' 

Still, the group got right to work, trying a wheelbarrow workout and cracking up as they lifted each other over their backs and held one another at awkward angles. 

Looks like fun: They giggle as they hold each other up and flip over each other in trust exercises

That's a wrap! Jenna admitted that it is much more fun to work out with friends, but she is done with on-air exercise segments

'The girls and I participated in a partner work-out that involved trust, strength, and lots of fun,' Jenna explained.

When all was said and done, it seemed like Jenna may have toned her stomach more with belly laughs than strenuous exercise - and she said exercising is certainly more fun with friends.

In fact, she pointed to a statistic that 80 per cent of people believe they're more likely to fit in work-outs and stick to their routines if they do so with a friend. 

But despite all that, hitting the gym with someone fun wasn't enough to get her to agree to do it again. Though some pressure from her Today show co-worker Savannah Guthrie got her to hit the gym one last time, Jenna decided to give up on her resolution on the couch this morning, saying she'd had enough with her on-air work-out segments.