Genesis 22:2
The LORD said, "Go get Isaac, your only son, the one you dearly love! Take him to the land of Moriah, and I will show you a mountain where you must sacrifice him to me on the fires of an altar."
The Bible speaks often of sacrifices for God. In fact, the first accepted sacrifices were made by God Himself for mankind.
Genesis 3:21
"The LORD God made tunics of animal skins for Adam and his wife and clothed them"
Sacrifices have been happening ever since in different ways. Sacrifice is a way to signify devotion. In today's age, however, we seem to have forgotten why it's necessary to sacrifice. We don't seem to understand it. We no longer have a clear way to show we are devoted to God and his ways.
In ancient times, taking the most valuable thing to you and burning it as a sacrifice would signify that you are devoted to the Lord.
Today, however, not all sacrifices are done in the Old Testament way of slaughtering or harvesting & burning our most valuable goods for God. We now sacrifice time by devoting ourselves to study or caring for the elderly or sacrificing a sum of money to help a coworker struggling to pay their bills because her husband suddenly passed away. Ultimately, whatever the root reason for your sacrifices is what you worship. If you sacrifice your time, money & energy to stimulate your nerve endings with sex, drugs & other passions, the root reason for your sacrifices would be the pleasure of self above all else, which is known as hedonism, and could be considered a false idol. If instead you sacrifice for the ends of acquiring money or other material goods, you worship mammon, a diabolical force of covetousness.
We are creatures of sacrifice whether we want to be or not. Every action you take or neglect is a sacrifice of something. Choosing not to participate in anything you know you should is a sacrifice. Not participating is sacrificing your future, your potential, and maybe even your health, not to mention the possibilities in your relationships that die through the lack of participation, which is the most important sacrifice in this example. It doesn't matter if it's your school you refuse to participate in or an invitation to climb Mount Everest or anything in between. If you feel compelled to do it you should do it for the glory of God. Otherwise, you will regret the life you have and yearn for the life that could have been.
The point of sacrifices is to glorify God. A byproduct of that is that God delights in empowering and blessing you or those you pray for, just often not In the way you expect.
What is a proper sacrifice to God?
God calls us to sacrifice that which is evil and that we love as a representation of the circumcision of the heart. It also symbolizes giving our sins to God to bear on the cross as a sacrifice for us. God told Abraham about his sacrifice of his son, "Go get Isaac, your only son, the one you dearly love!" This tells us it needs to be what we least want to give up. For you, it might be excessive alcohol consumption or meaningless sex with people you have no intention of building a relationship with. Or even things that are good but may play the part of an idol for you if you let it. In Abraham's case, it would have been easy and even likely for him to refuse God's request and see his only son as more important than the God who gave him his son. (Important side note) Isaac was estimated to be between 25-35 years of age, at this time as he was able to carry the wood required for sacrifice on a 3-day journey and later up a mountain. It would not have been possible for Abraham to overpower him as he was already an old man of 99 years when he left his father’s house, he would have had to go willingly and do most of the work to make this sacrifice possible. This is supposed to reflect what God intended to do in the future which is why before Abraham plunged the knife God provided a substitute sacrifice.
God loves humanity, so it would seem what's best to sacrifice is your time and effort towards making the world a better place. That could mean raising foster children. Or it could be mentoring young men or women in your community to teach them what is acceptable in the eyes of God and how to carry the burdens our lives put on us gracefully. It is all for the glory of God.
As Dr. Jordan Peterson likes to put it "Find the heaviest burden you can pick up and carry it as far as you possibly can". Whatever it is for you, know that sacrifice for God reaps rewards in this life and the next. Romans 12:1 says we should present our bodies as a living sacrifice to the Lord (on the altar of our lives).