Guard

"Be vigilant; guard your mind against negative thoughts."

"Guard against the impostures of pretended patriotism."

"I'm one of those people who fiercely guards their privacy, so I hate doing interviews."

"Always acknowledge a fault. This will throw those in authority off their guard and give you an opportunity to commit more."

"Guard well your spare moments. They are like uncut diamonds. Discard them and their value will never be known. Improve them and they will become the brightest gems in a useful life."