Celebrity trainer Tony Horton is best known for his very successful P90X at-home fitness program.

It was followed by P90X2, P90X3, and a number of smaller programs. Many have found success with the programs over the years, but they are definitely not easy.

We spoke to Tony recently and asked him what exercises people starting his programs have the most trouble with.

Here's what he told us:

"Well, I donít like to say thereís a universal truth there, because you know ó different athletes, different people, different stages of life ..."

"So, the ones that I her about from different groups - plyo (plyometrics) is a bear. If you havenít jumped off the ground in your life and Iím asking you to get up in the air and then learn how to land softly so you donít hurt your knees, that can be very problematic for some people initially so they have to modify, especially if they have a lot of weight to lose. But if youíve been a track athlete or someone whoís had explosive leg activities in your life, parkour or whatever, then plyo is hard but itís still do-able."

"Chest and back is another one too, I would say that the pull-up is a conundrum for a lot of people, especially women who have a lot of weight to lose. It just feels like itís impossible. I have a friend, this girl Paige, she couldnít do a pull-up at all. She had to use a pull-up assist band, she had to put all three of the little assist bands on there - she could do like 8 or 9, and now she can do like 4 - doesnít sound like a lot, but when you think about it, she lost a lot of weight and went from using a band to not having to use it at all. And sheís a 42-year-old mother of 3, who looks like sheís like a professional rock climber. I mean it was a solid 9 months before she went from Ďcouldnít do ití to 4, but she just didnít miss a day, you know."

"So for some people itís plyo, for some people itís pull-ups, and most certainly itís the yoga. The yoga is a crusher for a lot of men whoíve never done it before. A lot of big, strong, powerful, fast, athletic dudes - they do that hour and a half yoga class and they feel like absolute neophytes - fitness neophytes. And the smart ones come right back and do it again and again and again."

"I do event after event where people have my programs and know my stuff and have been through several rounds and Iíll look out and thereíll be 2,000 people out there and half of them are men or more and everyone knows up dog from down dog from chaturunga, from chavasana from a reverse warrior 2 ó they know what Iím taking about, they can all do it and 5, 6, 10 years ago they had no idea what I was talking about, couldnít even get close to it. There is a trend, itís changing and more men are getting it. But I would say itís those three: yoga, pull ups, and plyo."

NOW WATCH: This simple exercise will work out every muscle in your body

See Also:

This is the carefully planned diet of celebrity trainer Tony HortonCelebrity trainer Tony Horton says this is his absolute favorite type of workoutCelebrity trainer Tony Horton says this is the one thing people trying to lose weight mess up