I'm a Bemindful user. Bemaindful is "a free positive affirmations web service. It contains quality articles and hundreds of searchable positive affirmations that are categorized by keywords (tags) Signing up to bmindful allows you to create a list of selected affirmations and add your own personal ones. This list is available online at any time or you can print it out for offline access throughout the day" according to their websaite.
Anyone can post any affirmations. Some affirmations are useless, but it is alright if I can find a few good one which I like.