Meditating with a few friends at regular times can be a great support towards constancy of practice and development of wisdom. The solitary meditator eventually faces diminishing will-power, as there's often something else to do that seems more important (or more interesting) than watching the breath. Regular group meditation for an agreed-upon duration keeps the participants going, regardless of their flux of moods. (The investigation of these shifts of disposition often yields important insights, but on our own we can find it difficult to persevere with them.) As well as seeing the personal benefits, you can reflect that your efforts are helping others to keep practising.