A change of heart
To change one's opinion or attitude.

Change of scenery
A move to a different place, usually for a fresh perspective.

Change the tune
To change one's attitude or opinion about something.

Turn over a new leaf
To start behaving in a better or more responsible way.

Out with the old, in with the new
Removing old things and replacing them with new ones.

A breath of fresh air
A refreshing change.

Ring the changes
To vary the way something is done to make it more interesting.

The winds of change
Indications that important changes are coming.

Break the mold
To do something in a completely new way.

Shift gears
To change one's approach or method.

Change horses in midstream
To change plans or leaders in the middle of an important activity.

Roll with the punches
To adapt to difficult situations.

Make waves
To cause disruption or change.

Go with the flow
To accept things as they happen and not try to change them.

Turn the tables
To reverse a situation to your advantage.

Switch gears
To change your approach or strategy suddenly.

Out of the blue
Something that happens unexpectedly.

A new lease on life
An opportunity to improve or change one’s life.

Step up your game
To improve or make a significant change in effort.

Bite the bullet
To endure a painful or unpleasant situation that cannot be avoided.