Finding time out of your caring routine to do some exercise can provide both physical and emotional benefits. Not only does physical activity help to improve your heart health, reduce various health risks and increase your stamina, it can also help you emotionally. Doing something active for yourself that you enjoy is also an effective stress-reduction technique for many, helping you to cope with difficult situations.
NHS choices have produced an excellent webpage on exercise and fitness: https://www.nhs.uk/livewell/fitness/Pages/Fitnesshome.aspx
The Carers Trust have put together useful information about taking care of yourself with Taking care of yourself from Carers UK