Plenty of people start a new exercise regime in the new year, but as well as helping you lose the Christmas pounds, exercising boosts your immunity - and can help you to ward off the bugs which seem so prevalent at this time of year.
The benefits of being physically active extend beyond weight – it's really good for your heart, keeping muscles and bones strong, and we have helped to show that it is good for immune function as well.
We completed a study last year where we were looking at how much physical activity older people do and at their immune systems, and we found that in older adults who don't exercise, their neutrophils (a type of white blood cell) don't work as well. These are immune cells that help you fight bacterial infections such as hospital superbugs and pneumonia.
The study also showed that exercise can help with stress, something many people may suffer from at this time of year, with the return to work. When you're in a stressed situation you have high levels of the stress hormone cortisol, and if it's raised for an extended length of time it has lots of negative effects that will have an impact on healthy ageing - things such as raising blood pressure, increasing muscle and bone loss, lowering mood and it can affect your distribution of fat, so you lay more fat down centrally around the abdomen.
Certainly having high levels of cortisol is associated with shorter lifespan, so if you can lower those levels it's going to be beneficial, and exercise is one way to do that.
And the best news is that the exercise programme does not need to be drastic. Regular brisk walking is excellent, as is swimming and the latest exercise fad of High Intensity Training (HIT or Fast exercise) - so anyone starting out on a new exercise regime can start on a programme they are confident of being able to complete and keep the winters bugs and blues at bay!
Janet Lord is Professor of Immune Cell Biology at the University of Birmingham.