Relative rest does not mean completely resting from any activity or weight bearing. What it means is a modification to your current day to day regime so that you are minimising activities which make your pain worse. For some, this may be reducing the weekly mileage or frequency of running if their pain is linked to running or that they suffer the day after a run. For more severe cases it may mean complete rest from running until the pain has improved. If you notice that spending excessively long hours on your feet aggravates your symptoms then try to reduce the amount of time you spend on your feet. This is difficult for people whose job role requires periods of continuous standing. If it is possible to take a break and take some weight off your feet throughout the day then this is highly recommended and can help with recovery.
The plantar fascia becomes injured when the level of stress placed on it exceeds the amount the stress the plantar fascia can tolerate, therefore in order for the plantar fascia to heal you need to reduce excess stress on the plantar fascia to an amount it can tolerate without becoming over stressed or injured. If relative rest is overlooked it can reduce your chances of healing despite trying other treatment options such as stretching, orthotics, night splints etc. Relative rest is the most simple of all the available treatment options and one of the most important as your body cannot heal without sufficient rest so make sure you find time to help your body so that it can help you.
It is important to understand that relative rest alone, whilst helpful for reducing excessive stress on the plantar fascia, is often not enough to resolve plantar fasciitis and this simple treatment principle should be followed along with additional treatment options that address the underlying cause of the pain, which is unique to each individual.