As you might imagine, Liam’s washboard waistline is a result of an intensive workout routine. Fortunately for us, One Direction showed the world how they remain fit in a 1D Day Livestream video a couple years back. The regimen includes a bit of mixed martial arts, boxing, and circuit training. That definitely explains what Liam's got going on under his shirt.In the livestream video , Liam remarks, “Being out there jumping around like a lunatic each night, and we're 126 shows in now, it's quite crazy. Staying fit is a huge deal."