There's an old saying in the business world — "If you stand still you're going backwards." Products change, competition gets more aggressive, and everything is moving. If you stand still it won’t be long until you're out in the cold.

In Christianity it is even more important to continue to be alert and grow. Satan never rests - Satan NEVER rests - and if we rest, he'll take advantage of the opportunity.

God recommends we never let up. God commands that we struggle and fight the devil to the end. Jesus said...
"... it is the one who has endured to the end who will be saved."

-- Matthew 10:22

As Peter encourages Christians in his letter he says...
Therefore, gird your minds for action, keep sober in spirit, fix your hope completely on the grace to be brought to you at the revelation of Jesus Christ.