Now the time has come for Jesus to announce His Passion to His disciples. Jesus has not come only to teach but to open the door leading to the Resurrection, that is, life eternal. And, since His disciples now know Him as the Messiah of God (v 20), they must learn that there is no salvation if death is not conquered.
Immediately Jesus adds that His disciples must share in His victory over death; each must deny himself, take up his cross each day and follow Him.
To deny the self is the fundamental orientation of the life of a Christian. This means choosing serving over being served, sacrificing oneself for others over taking advantage of others, seeking not so much to be consoled as to console, to be understood as to understand, and to be loved as to love. This is contrary to the general orientation of worldly life: that is, being only concerned about not doing bad things and pursuing ambitions and enjoying life to the full at the expense of nature and humanity.
The Lord wishes a cross for each one of us to bear every day, so we accept and bear it and follow Him, who is bearing His Cross for the world! This way, we share His Passion and Victory, as He has promised!
May God be blessed!