Thanks very much for your question.
You are quite right about the hope of eternal life being a large part of the motivation for some people to follow Christ. There is nothing wrong with that because, it takes a great deal of faith to put your trust in something the absolute truth of which will only be confirmed for you after you die!
Jesus said, in John 10:10, I am come that they might have life, and that they might have it more abundantly. He is referring not just to the quantity of life but to its quality.
It is honourable of you to want to follow Jesus with no thought of reward. However, if the reward for faithful service is eternal life, like it or not, isn't that just the icing on the cake? Why not rejoice in this beautiful gift of God?
Romans 6:23 For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord.
1 Corinthians 2:9 But as it is written, Eye hath not seen, nor ear heard, neither have entered into the heart of man, the things which God hath prepared for them that love him
Eternal life is not just a quantity but it means that one day, time will have no meaning for us because we will enjoy perfect fellowshiip with God and the Lord Jesus Christ and also with one another. It has to do with the lifting of the curse of the futility of degeneration and death inflicted on creation and ourselves because of sin.
Romans 8:18-23 For I consider that the sufferings of this present time are not worth comparing with the glory that is to be revealed to us. For the creation waits with eager longing for the revealing of the sons of God. For the creation was subjected to futility, not willingly, but because of him who subjected it, in hope that the creation itself will be set free from its bondage to decay and obtain the freedom of the glory of the children of God. For we know that the whole creation has been groaning together in the pains of childbirth until now. And not only the creation, but we ourselves, who have the firstfruits of the Spirit, groan inwardly as we wait eagerly for adoption as sons, the redemption of our bodies.
You are seeing the desire for eternal life as a selfish thing. Why not look at it for what it is, a wonderful opportunity to enter into a real, abundant life in fullness of love and fellowship with God and all who love Him. [see 1 Corinthians 15:28]. I think we will be very busy too. After all, it is a very large universe we live in.
I hope you have found this helpful.