As Paul Roberts finished the second month of the Fitness Challenge sponsored by Core Fitness and Out & About, he was beginning to reap major benefits.

Roberts has lost 12 lbs. and has experienced an increase in his aerobic capacity, but what most impresses him is that his back hasn’t been hurting—despite increasingly strenuous exercises. The 43-year-old Barclays employee has a history of back problems, including two surgeries due to herniated discs.

“It’s kind of nice just to be sore after a workout, rather than having actual pain,” Roberts says.

Arianne Missimer, owner of Core Fitness, is overseeing Roberts’ program. “Each workout is much more intense than the previous, because Paul is continuously progressing,” she says. “His overall strength and his movement patterns have improved significantly, his endurance is much better, and he is able to work at a much greater capacity.”

Roberts confirms this. “I don’t have to take breaks between exercises now.”

Missimer says during the first month she concentrated on improving Roberts’ posture. “This will be continued throughout the year,” she says, “but it has improved tremendously. He has learned to find his ‘neutral’ position, and then through exercise, we are reinforcing that. For example, lengthening his chest and shoulder muscles, while strengthening the muscles that support the shoulder blades—the scapula. This is a very important part of core training, because poor posture leads to a weakened core and vice versa.”

As for diet, Missimer has increased his protein intake in an effort to preserve lean muscle. Roberts’ weight loss occurred a little too fast, according to Missimer, but only 1 percent body fat was lost. “If he had not lost it so fast, the percentage of body fat lost would have been greater. But, the important thing is that we are heading in the right direction.”

Roberts says he has more energy and endurance, and the climb up the steps to his third-floor office is no longer so arduous. “I don’t get winded anymore,” he says.

“He comes in on his days off to do cardio,” says Missimer. “He’s an excellent student.”