It is a beautiful day here in Japan. Almost 20 C on February 20th, 2019.
Today's phrase is "warm up".
This means to do a light practice before a sport, or dancing, or playing music, etc.
Example 1
The football game has not started yet. The team is still warming up .
Example 2
A. Are you going to warm up before weight lifting?
B. Yes, I'll do some stretching first.
https://dictionary.cambridge.org/dictionary/english/warm-up