Integrity is about determining to walk the right path. It is really hard to have integrity on our own... That's why we ask for God's help.
It is refusing to pursue low and vulgar things.
Integrity is doing the right thing, even when no one is looking. - CS Lewis
Integrity is what happens in our home where no one else sees, but our own heart certainly knows.
You do not wake up one morning a bad person. It happens by a thousand tiny surrenders of self-respect to self-interest. - Robert Brault
One good way to decide in advance is to tell someone else what you're planning to do.