meaning - What does the phrase 'take your time by me' mean?

Passage:

Arms bending and stretching!' she rapped out. 'Take your time by me. One, two, three, four! One, two, three, four! Come on, comrades, put a bit of life into it!

(George Orwell 1984)

Question:

What does the phrase 'take your time by me' mean?

Link to the book (page #40)

Answer

Judging by the repeated counting from one to four afterwards, this is an instruction to follow the tempo, or rhythm, set by the speaker.