Actually, the flesh serves a vital purpose.
Flesh made its debut when God bundled up a bunch of clay, breathed His life into it, and it became "man." It became a "living soul."
But God saw that this hunk of clay was lonely, so He performed the world's first major surgery — removed a rib, bunched up some more clay and made a "woman."
For a little conjecture, one might imagine Adam's first response could have been, "Whoa! What a woman!" However, the words came out of him, "This is bone of my bone of my bones, and flesh of my flesh." Either way, I think he was pleased!
Scripture describes the flesh as "earthen vessels" (2 Corinthians 4;7) and a "tabernacle" (a tent — 2 Corinthians 5:4) .
This flesh — "or tabernacle of clay" — houses the real you: your soul, your spirit. You cannot move about in the physical realm without it. The flesh is able to feel pain — and experience euphoria — and it plays a vital part in procreation, recreation and, provided it's not lazy, it works by the sweat of its brow — or "in the sweat of thy face" (Genesis 3:19 -King James Version).
Boys and girls in college would be hard-pressed to hunt down and woo the person who is to be their life's mate without it. We perfume it, fix its hair, cover its blemishes, and dress it meticulously — in order to attract that life's mate. It comes in real handy when you are performing in your livelihood. It's hard for a pipeliner to function without it. And it gives the congregation something to look at while the preacher is preaching.
So the flesh has a vital function on this earth. Yet scripture says that it is useless when it comes to bringing glory to God.
Romans 8:8: "So then they that are in the flesh cannot please God."
One who lives his or her life only by the whims, passions and sensations of the flesh cannot perceive God.
1 Corinthians 2:14: "But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned."
You cannot clean up your flesh, employ human ingenuity, and come to God, announcing to Him that you are now worthy of Him. It doesn't work that way. You come to Christ broken and "undone" because of the sin of the decrepit flesh — asking Him to deliver you from this flesh (or as Paul said in Romans 7, "this body of death") and make your spirit alive in Him.
It is at that point God transforms your life and makes you (not your flesh, but YOU) fit for heaven.
"Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption." 1 Corinthians 15:50
So do you want to go to heaven when you die? Well, it is possible for you to go there, but you won't take your flesh with you. It will return to the dust from whence it came. Only the real you inside that "tabernacle" (your spirit) can inherit eternal life.
Meanwhile, here on earth, life is filled with joy and fun — and a constant battle against evil passions, which invades this old flesh.
I guess you could sum it up this way — "The flesh — you can't live on this earth without it — but you can't live in heaven with it."