Here is a snippet from Beyond Blue
Exercise is important for maintaining both good physical health and mental health.
Start small and build up slowly - If a person is going through a period of depression, they may have difficulty with simple things such as getting up and getting dressed in the morning. Don't try to do too much too early. It's a good idea to start with easy activities and slowly build on them.
Include other people - When people don't feel like doing much, planning social outings/activities can help them get moving. If the person doesn't have an established social network, they could consider joining a local club or group.
Don't be too hard on yourself - A plan is only a rough guide that should be flexible. If an activity runs overtime or can't be completed, skip it and move onto the next one.
Reward yourself - Allow time to do enjoyable, interesting, relaxing and satisfying activities. Some cheap, entertaining and easy pass-times include reading, listening to music, watching movies, gardening, going to the beach or park, taking part in sporting or creative activities, shopping, seeing friends and playing with pets.