If you were diagnosed with cancer more than five or 10 years ago, you might have been told to rest and avoid physical activity.

Today, it's a different story: we now know exercise benefits most people both during and after cancer treatment.

In May, Australian cancer experts launched a "world-first" position statement calling for exercise to be prescribed to all cancer patients as part of their routine treatment.

But how do you best keep physically active in the midst of illness, and later, remission?

Here are a few things to keep in mind when it comes to exercise in cancer care.

Exercise can alleviate side effects

While treatment pathways vary from person to person, cancer therapy (and cancer itself) can take a hefty toll on your physical and mental health.

Cancer-related fatigue is one of the most common side effects of cancer treatment and can occur at any stage of the disease. Other side effects include reduced fitness, muscle weakness, difficulty undertaking daily activities, as well as depression and anxiety.

Although some of these problems may begin before a cancer diagnosis, they are likely to be exacerbated during treatment.

The good news is that exercise can help to alleviate some of the side effects of cancer and its treatment, and improve outcomes for people with cancer.

Staying active helps to maintain or enhance your physical fitness, reduce fatigue, relieve mental distress and improve your overall quality of life.

Research shows exercise can help people with cancer tolerate aggressive treatments such as chemotherapy.

There is also data to suggest that in some types of cancer, such as breast, colon and prostate cancer, exercise may improve rates of survival.

Try a combination of cardio and weights

The are two types of exercise you need to focus on during (and after) cancer treatment: cardio exercise and resistance exercise.

Cardio exercise is all about getting your heart pumping and your whole body working. Think brisk walking, jogging, cycling, swimming and dancing.

Resistance exercise, on the other hand, is about strengthening your muscles. This can be done using weight machines, dumbbells, elastic bands or just gravity and the weight of your own body.

When it comes to cardio, 150 minutes of moderate intensity exercise per week is the goal. You might achieve this with 30 minutes of brisk walking or cycling (on an exercise bike) five times a week.

If you find 30 minutes in one session is too challenging, begin with a 10-minute brisk walk and slowly build your way up — either by extending the duration of your walk each time, or adding more walks into your day.

The intensity — or how hard you exercise — is important too. The easiest way to work out how intensely you're exercising is by using the "walk and talk" test.

If you are walking for exercise, you need to be walking fast enough that you are getting a bit puffed (moderate intensity) — but not so fast that you can't speak in full sentences (vigorous intensity).

Although vigorous intensity exercise gets your heart rate up (and requires only 75 minutes per week, compared to 150), we don't recommend starting with this unless you are a very competent exerciser or have the support of a health professional.

When it comes to resistance training, research shows exercises should be done two or three times per week involving exercises that target the major muscle groups.

If you haven't exercised for a long time, start off slow. And remember: when it comes to exercise, something is always better than nothing.

I've started exercising, but how do I stay motivated?

Staying motivated can be hard, especially on the days when you are busy running to and from hospital appointments, or sitting for hours in the hospital to receive chemotherapy.

It's even harder on the days when symptoms like fatigue are at their worst.

The first thing to think about is what works for you. If you're someone who likes tracking your own progress and striving to improve your fitness levels, measuring your daily step count might be a good option.

Watching how many steps you take each day and challenging yourself to reach a daily goal is a great way to keep motivated — and it helps you keep track of your daily activity.

If you have a smartphone, most come with a free health app that can track your daily step count.

Another way to maintain motivation is to use an exercise diary; many people find it really satisfying to tick a box for each day they exercise. Plus, it gives you the chance to marvel at your efforts at the end of each week.

While many people prefer to exercise alone, some people find it boring. If this is you, think about asking a friend to join you, or see if your community has a local walking group or exercise class for people with cancer.

What about after cancer, can I stop now?

No way! Keep it up. Or start again if you have stopped.

Exercise for people in remission — both immediately after treatment and in the long term — is really important. Surviving cancer means you are at risk of several other chronic diseases including diabetes and cardiovascular disease.

Evidence tells us that exercise helps prevent these diseases, plus a growing body of evidence suggests exercise has a role to play in preventing the cancer coming back.

Maintaining a healthy lifestyle after cancer is more important than ever.

If you are currently undergoing cancer treatment (or are due to start soon) and planning to exercise, it's a good idea to speak with your GP first. They'll be able to refer you to an exercise specialist with experience in cancer care, such as a physiotherapist or accredited exercise physiologist.