What does it mean to be zealous for the Lord?

The following is J.I. Packers description of a zealous man from "Knowing God."
"A zealous man in religion is pre-eminently a man of one thing. It is not enough to say that he is earnest, hearty, uncompromising, thorough-going, whole-hearted, fervent in spirit. He only sees one thing, he lives for one thing, he is swallowed up in one thing; and that one thing is to please God. Whether he lives, or whether he dies - whether he has health, or whether he has sickness- whether he is rich, or whether he is poor- whether he pleases man, or whether he gives offense- whether he is thought wise, or whether he is thought wise, or whether he is thought foolish- whether he gets blame, or whether he gets praise- whether he gets honor, or whether he gets shame- for all this the zealous man cares nothing at all. He burns for one thing; and that one thing is to please God, and to advance God's glory."

Phinehas was a zealous man. His zeal saved the Israelites. Numbers 25:5-13

Am I zealous? Are you? Are we all designed to be this zealous?

When I read such a description of zeal and stories about such zealous men I am dishearted. I think "How can I achieve this!?" I look at myself and see such a lack of zeal for God's glory. I predominantly live my life for myself and not for Christ as I am commanded to in
2 Corinthians 5:14-15.

God I long for such zeal and ask for it, but praise be to you because you no longer regard me according to the flesh. 2 Corinthians 5:16