Lacoste, who has garnered national attention for his annual fitness challenge series Fit 4 Change, contracted West Nile Virus this fall and then experienced life-threatening complications.
For about a week, the man who would typically run for 30 minutes to an hour each day had to use a walker.
Now, "I'm back," 38-year-old Lacoste said. "I'm ready to go. I'm ready for the new year. I'm ready to inspire and coach a whole other group of people from across our state."
Lacoste said the experience has strengthened his passion for fighting obesity in Mississippi. He also wants to help raise awareness of the dangers of the mosquito-borne virus.
Toward the end of the summer, Lacoste began having headaches and neck pain. He had other symptoms, too, including exhaustion.
After noticing his right upper quadriceps were severely swollen, Lacoste went to his primary care doctor, who put him on antibiotics.
That was the first in a series of tests and procedures that included surgery to drain hematomas — pooled blood — that had been found in Lacoste's leg.
He was walking into his house with his 2- and 5-year-old sons when he felt a sharp pain in his upper thigh muscles. The next morning, he said, "I started having full-blown muscle convulsions all over my body. I fell out."
Lacoste was rushed to the hospital.
He had a fever that would not subside. Nurses would frequently have to change his sheets, which were soaked with sweat. Catholic priests at St. Dominic Hospital stopped in his room and prayed.
Lacoste said it was scary not knowing what was wrong. Doctors ran test after test before confirming he had severe West Nile disease.
Mississippi had 250 confirmed human cases of West Nile Virus in 2012 — about five times more cases than in 2011, according to the state Department of Health's website.
Five Mississippians died of West Nile in 2011 and in 2012, according to the state Health Department.
Lacoste said the virus attacked his spinal column. When he tried to move or walk, "nothing was firing correctly" because of the damage to his nerves and spinal column, Lacoste said. He was having micro tears all over his body. He also had all the symptoms of meningitis and polio.
"I'm very lucky to be alive," Lacoste said.
Lacoste has lost about 30 percent of the strength in the right side of his body. He's again lifting weights, walking and jogging to regain that strength.
For now, he said, he's lifting weights that before he wouldn't have used to warm up. Lacoste has gone from a typical workout with 115-pound dumbbells to one using 50-pound dumbbells.
He would run about four or five miles in half an hour. Now, he said, "I'm able to run about a mile before I'm just exhausted."
"A lot of times I do get really tired late in the day," Lacoste said. "I can still feel that I'm not 100 percent as far as my own personal strength. But my ability to work and perform as a coach, I'm all there."
Lacoste's approach as a fitness coach is often described as tough, hard-nosed, passionate.
Or, as state Rep. Steve Holland put it, "Paul's mean as hell. He's just an absolute freakin' tyrant. But he knows what he's doing. He's very committed."
Holland, D-Plantersville, participated in the first Paul Lacoste Sports Fit 4 Change program in 2010, and he plans to participate again this year despite complications from a total knee and knee cap replacement surgery.
"Thanks to the mental and physical training that Fit 4 Change brought to me, I just live in a world of wellness now and physical activity," Holland said. "I have learned how to moderate my diet. I have learned how important it is to habitually exercise if it's nothing but walking 30 minutes a day."
Holland continued working out and making healthy choices when he returned home. That effort, Holland said, has spilled over to his family, friends and constituents, as well as peers at the Capitol.
"It just keeps on keeping on, and that's the beauty of it," Holland said.
Lt. Gov. Tate Reeves lost about 18 pounds in a class with Lacoste over the summer.
He also shaved about 2.5 minutes off the time it takes him to run a mile. He also doubled the number of push-ups and sit-ups he could complete.
Reeves plans to participate in Fit 4 Change again this legislative session.
"His hard-nosed nature really inspires the people who are in the class to do better and better," Reeves said of Lacoste. "You can see it. The classes are at 5 and 6 in the morning, so the individuals there, they are making a sacrifice."
Those participants have also made the decision to improve their overall fitness level, and almost every member of the summer class finished the program, he said.
"I think that Paul's passion for improving the overall health of Mississippi and Mississippians comes through in every single class that he does," Reeves said.
That passion is contagious, he said.
Rep. Mary Coleman, D-Jackson, has also seen success in the program and plans to participate again.
"Personally, I've toned up. I've lost weight, my blood pressure went down," she said. "I'm just doing it because I want to stay as healthy as I possibly can."
Lacoste is "very firm," she said.
"It doesn't matter whether you're a legislator or state employee or an ordinary (resident). He treats us all the same. He hollers at all of us.
"You have to have a strong stick-to-it-iveness in order to stay there because sometimes people's feelings get hurt," Coleman said.
Those who participate for the right reasons can endure, she said.
With Fit 4 Change, said Rep. Hank Zuber, R-Ocean Springs, there are two dynamics working together to cause "tremendous" weight loss: Lacoste and teamwork.
"I joined to get back into better shape and to be more healthy and to lose weight," Zuber said.
He has met those goals each time. He's aiming to lose about 18 pounds this time.
When he first participated in Fit 4 Change, Zuber's challenge was to endure the 45-minute workouts.
"I was hardly able to do any sit-ups and push-ups," he said. "Obviously after that first week, your body is very sore and your muscles are very sore."
So he had to get through the soreness and lack of stamina.
"Then the weight just comes off.
"This is what he (Lacoste) lives for, and it's his goal to not only just change the people who participate in his class, but to change the entire state and to make all Mississippians healthier," Zuber said.
Lacoste said he now knows what it means to have to start over.
"For me, when I first started training, I was in seventh grade. I've always trained," Lacoste said.
Training continued to be a key part of his life as he played football in high school, college and as a professional.
"I just can't imagine not sweating in a day," Lacoste said. "To me, that's just part of what you should do."
Despite the setback, Lacoste is thankful.
"I think he (God) put me down for a while physically so I can realize how much I love what I do and I need to be as strong as I can be. I need to be as healthy as I can be to continue to push this message forward for Mississippi."