OK, if one can be a slave to the flesh and still be generous and care deeply about others then I don't mind so much being a slave to the flesh. It's a very negative way of putting things though. I think it would be a tragedy to waste your life without paying attention to it. The belief that this is it, not just a trailer for the feature pesentation, is actually very life affirming. It makes it clear just how precious life is.
Years ago I knew this very devout Christian girl, and we both knew a baby who died in really grim circumstances. I was devastated but I honestly think it made little impact on her. She just said that it was part of God's plan and that the baby was in heaven and then carried on as before. Since then I've found Christian detachment from the world rather disconcerting
The Bible regards being a "slave to the flesh" as a "slave to sin", meaning, you didn't have a choice whether to sin or not, you will naturally always choose the more sinful path. That's why the NT talks so often of being "free" from sin, we now have a choice to be good or bad, where as before we didn't.
It's still possible for a non-Christian to possess some of the fruits of the spirit, but they will never come to full fruitation without God tending them.
I, and all the other Christians I am friends with, don't disregard the worries and sadness of this world. Jesus himself didn't come to ignore those in need, he came to heal them and reach out to them. And, he commands Christians do the same. To make a general assumptions that Christians don't value this life is very disingenious to all of us who do. My heart would break the same for a family who lost a child regardless of the fact of that child being in Heaven now.
The Christian view does not teach us to ignore pain, because the NT states clearly we will suffer, but instead not to lose hope through it.