Jesus is saying, "It's not enough just to know me as a teacher or as an abstract principle; you have to look at my life. I went to the cross--and on the cross I lost my identity so you can have one.
Once you see the Son of God loving you like that, once you are moved by that viscerally and existentially, you begin to get a strength, an assurance, a sense of your own value and distinctiveness that is not based on what you're doing or whether somebody loves you, whether you've lost weight or how much money you've got. You're free--the old approach to identity is gone. Nobody put this better than C. S. Lewis in the last two pages of his Mere Christianity, where he comments on Jesus' call to lose yourself to find yourself:
The more we get what we now call "ourselves" out of the way and let Him take us over, the more truly ourselves we become ... our real selves are all waiting for us in him ... The more I resist Him and try to live on my own, the more I become dominated by my own heredity and upbringing and surrounding and natural desires. In fact what I so proudly call "Myself" becomes merely the meeting-place for trains of events which I never started and I cannot stop. What I call "My wishes" become merely the desires thrown up by my physical organism or pumped into me by other men's thoughts ... It is when I turn to Christ, when I give myself up to His personality, that I finally begin to have a real personality all of my own ... [Nevertheless], you must not go to Christ for the sake of [a new self]. As long as your own personalitty is what you are bothering about you are not going to Him at all.
If you go to Jesus to get a new personality, Lewis says, you still haven't really gone to Jesus. Your real self will not come out as long as you are looking for it; it will only emerge when you're looking for him.
"Whoever desires to come after Me, let him deny himself, and take up his cross, and follow Me. For whoever desires to save his life will lose it, but whoever loses his life for My sake and the gospel's will save it." -- Mark 8:34-35