The former Miss Ireland (21) has been hitting the gym with a vengeance and is now reaping the benefits of all that hard work.
Holly, who is dating Leinster rugby star Cian Healy, explained how she was prompted into signing up with a personal trainer last May after joining Andrea Roche's agency and was determined to look her best.
"I've been going in every day from Monday to Friday and then sometimes I might go twice a day if I have time.
"Then on Saturday mornings, I've been going to Yoga classes just to stretch out the muscles, so it's been going great," she said.
"My trainer Sophie is the same age as me and we get on great, it's like going in to meet a friend and have the banter. So I think that definitely helps me get up at 7am and head into town as I don't want to let her down by not turning up. We usually do about 35 to 40 minutes of circuit training and weights so it's short bursts of exercise to get the heart rate up."
For Holly, it is a case of looking toned and fit, rather than constantly counting the calories and she said the approach paid off as her weight dropped gradually over the past six months.
"Sophie kept telling me to ignore the scales and just concentrate on the exercise and it's really worked. It's great to feel confident in whatever I'm wearing and know that I look toned," she said.
The Raheny beauty added that it helps having a boyfriend who's also a sports star and that Cian (25) has been very supportive about to her new eating plan. The pair, who both donated paintings to last night's Chernobyl Children's Secret Art exhibition, have been dating for nearly a year and are obviously a positive influence on each other when it comes to sticking to their regimes.
"It's so good that I'm with someone like him as we'd encourage each other and it's not like we're sitting in all the time ordering take-aways together. Having said that, he can more or less eat what he likes as he burns it all off in training," she added.