The daily life of a person involves many different activities, states and emotions, at times disconnecting one from remembering Allah Most High. Shaykh Abdur-Rahman mentions the main 4 states and the simplest way in remembering Allah in each of them.
A person can either be:
1) expressing happiness
2) upset, finding themselves in a testing, difficult situation
3) remembering a sin of the past
4) worrying about the future