Celebration of discipline by Richard Foster was first published in 1978 and has been republished several times, most recently in 2008. For a book to remain in print for over 30 years is quite amazing.
In his book, Foster covers 12 disciplines which have been practiced from the earliest days of Christianity and still believed to be important for spiritual growth. The 12 disciples are: meditation, prayer, fasting, study, simplicity, solitude, submission, service, confession, worship, guidance, and celebration. These are not presented in a legalistic manner; neither does he suggest following these exact disciplines is the only way to spiritual maturity. Rather they are presented as aids and tools to be used in the way the individual finds most beneficial. Furthermore Foster also suggests variations within each discipline of how they might be employed. Of course, taking on a new spiritual discipline is never easy to maintain but Foster encourages people to persevere even if there is little benefit to begin with.
Foster looks at these disciplines from a different perspective to the norm and makes them sound like fun rather than a chore. His last chapter on celebration was particularly encouraging as he pointed out that joy was the whole point of engaging in these disciplines.