1) Resting on Laurels
After Barcelona FC won the Champions league in 2011, many believed they have since played badly because they were resting on their laurels
The General did not mind losing the last battle in his long career, because he could rest on his laurels
Although the trade union strikers went back to work, the managers should not rest on their laurels
Definition: Be proud of past achievements
Etymology: From Ancient Greece times, laurel leaves were closely tied to Apollo, the god of music, prophecy and poetry. Apollo was usually depicted with a crown of laurel leaves, and the plant eventually became a symbol of status and achievement. Victorious athletes at the ancient Olympic Games received wreaths made of laurel branches, and the Romans later adopted the practice and presented wreaths to generals who won important battles. Venerable Greeks and Romans, or "laureates," were thus able to "rest on their laurels" by basking in the glory of past achievements. Only later did the phrase take on a negative connotation, and since the 1800s it has been used for those who are overly satisfied with past triumphs.
2) All guns blazing
Mrs. Roberts went to the principal's office all guns blazing after she heard her son was suspended
Simon went into the debate all guns blazing, determined not to let his rival win
George went into the job interview all guns blazing
Definition: With much force and energy
Etymology: Shooting around
3) Pull the trigger
Although I know the family has nowhere to go, I may need to pull the trigger and evict them for late rent payments
The General pulled the trigger on a dangerous mission
Sharon pulled the trigger on burning her house to get insurance money
Definition: To make a decision that may very well require inflicting a result that is detrimental to self or others.
Etymology: From shooting a gun