When your identity is rooted in Christ, its definition and reference point is Christ - not your feelings or circumstances. This means that your circumstances and feelings have no capacity to give you an identity or measure it. We must not subcontract our feelings or circumstances to give us a measure of our identity. Only God, who is the creator and sovereign has capacity to assign value and identities, everything else will give you a false identity or value.

As long as God has not changed your purpose and value in His creation plans, nothing else can change your identity.  

"For I am the Lord, I do not change; therefore you are not consumed, O sons of Jacob." - Malachi 3:6. This verse shows that God does not change. Therefore when your identity is anchored in God (Christ), it will not change based on feelings or circumstances around us. You will not lose your identity because you feel low or because you are struggling financially.