05/12/2016 12:06 GMT | Updated 06/12/2017 05:12 GMT

Keeping Fit On The Road - Amy MacDonald

e-anjei via Getty Images

I think people are often shocked by me. I go to the football every week, I listen to Talksport religiously and I had so much positive feedback when I appeared on Top Gear talking about 0-60s and break horse power... To add another thing to my list - I'm also a bit of a fitness machine.

My boyfriend is a professional sportsman and we have a long running joke about who is the fittest. It started off as a tongue in cheek teasing, but as my obsession with sport has grown so has "the joke"!

Trust me, I come from a couch potato background... I was a chubby teenager more interested in crisps than cardio. But when my friend Rosie recently took me to Roehampton University for a series of energy expenditure tests (as a birthday treat!), I was overjoyed at my results. It was so interesting to learn that you can improve your metabolism through exercise. I always believed that our metabolism was just something that we were born with and those lucky slender people were just blessed with a fast metabolism.

Since starting my fitness drive I've managed to get my RMR (resting metabolic rate) up to 2193 calories per day. That's what I have to eat to maintain my weight - if I lay in bed all day. To put that into perspective, the normal RMR for a female of my characteristics would be 1482 calories per day. The most interesting aspect of this is that I'm not an athlete, I've never had an expensive personal trainer and I wasn't a child at all interested in playing sports.  I'm just like many other women trying to be a little healthier, and my love for fitness started in a very unassuming place - my living room floor.

I first got properly into fitness about 3 years ago now. I was single for the first time in years, and I know it sounds like a tired, old cliché, but it was so refreshing to be able to just focus on myself without worrying about anyone else. I'd also just returned from a week in New York. 7 days of American portions would send anyone on a fitness crusade.

I fell in love with Jillian Michaels - the incredible American fitness guru. She has an armoury full of at home fitness DVDs and 12 week plans which seemed perfect for me. If I ever went to the gym I'd simply plod away on a treadmill or half arse some squats. These DVDs forced me outside of my comfort zone.

I was so hooked on doing my morning DVD that I started to panic about the two-month tour I was about to embark upon. How would I be able to do my Jillian DVD? Not to worry - I took my laptop along, a stash of DVDs and every morning I would raid whatever hotel gym we were staying in and steal some hand weights. I managed to keep up my routine throughout the whole tour and it completely changed my mindset on health and fitness.

For anyone like myself, who came from relative couch potato to full blown 6 days-a-week warrior, you know the feeling, the moment it twigs and you realise that excuses are exactly that. Excuses. It took me no more than 30 minutes to do a DVD, I didn't need any space or fancy equipment yet I was now in the shape of my life, I was sleeping better and I had the most amazing Christmas after returning from tour. I felt happy, confident and comfortable in my own skin and I realised that it's a choice that we all have.

I'd urge everyone to find your Jillian Michaels. Find the thing that you enjoy, the thing that pushes you to the next level and makes you so proud when you get there. I can't imagine my life without fitness now and although I no longer do my trusty Jillian DVDs I've moved on and found other things I enjoy doing. Fitness to me is like brushing my teeth; it feels weird if I don't do it. I believe that anyone can get there but the body can only achieve what the mind lets it.

I'm looking forward to the next steps in my fitness journey and I plan to return to the University and do some more tests on my fitness and metabolism. It doesn't take a lot to get started and I truly believe that anyone can get there. To quote my heroine Jillian Michaels - every accomplishment starts with a decision to try.

New album 'Under Stars is released on 17th February