put the brakes on vs step up

put the brakes on

verb
  • To cease to perform one's current activity or to decrease one's level of activity. 

  • To stop (an event, action, or process) or to slow it down. 

step up

verb
  • To increase, augment, or advance, especially by one or more steps. 

  • To assume or take responsibility. 

How often have the words put the brakes on and step up occurred in a corpus of books? (source: Google Ngram Viewer )