When we make a spiritual declaration, what we are doing is aligning ourselves with what God says about us or others. In announcing and revealing ourselves to be on God's side, we immediately disassociate ourselves with any lies of the enemy and any access he had into our lives because of those lies.
1 John 2:12-14 can be turned into declarations that we speak over ourselves and others.
12 I am writing to you who are God’s children because your sins have been forgiven through Jesus.
Declare: "I am God's child and my sins have been forgiven through Jesus"
13 I am writing to you who are mature in the faith because you know Christ, who existed from the beginning.
I am writing to you who are young in the faith because you have won your battle with the evil one.
Declare: "Though I may be young in the faith I have won my battle with the evil one."