1. Ask a student 'What was the first thing you did this morning?'
2. When he/she has answered, you can go on asking the same question, or even better, make little variations like 'What was the first thing you saw this morning?'; or 'Who was the first person you met this week?'
3. After a few answers you can prompt students to take over asking the questions. This is one of the warmers that can be used often, because it's so variable.