The simple reason Christians may suffer more is because more is expected out of us!
Compare being humble and meek, give our life for His cause, turning the other cheek vs. being prideful and boasting, live for our carnal desires, and seeking revenge.
Hmmmmm, which one would you naturally pick? There is a theory of mind (can't remember official title) but basically states that humans naturally seek maximum pleasure and minimum pain.
I have met and seen Christians who are miserable and suffering based on their interpretations of beliefs, just holding on until Jesus comes. There is an expectation to suffer based on some of the Lords word and for some Christians and it becomes a self fulfilling prophecy. For others, they don't expect it and still suffer. Some are here on earth for a vacation - have all needs and wants met, extremely happy with life, believer and non-believers but those are more rare but are a reality.
It is a spectrum of suffering and rains on the just and unjust alike.
So, add the self-fulling prophecy and standards to live up to for His sake, it is easy to see why Christians appear to or do suffer more.
However, through my spiritual evolution, I have noticed that God wants us to enjoy being here in the physical world too!
We have His OK to be OK - and joyful!
After all, it is His will we are here and we must celebrate that.
Until now you have asked nothing in my name. Ask, and you will
receive, that your joy may be full.
He who goes out weeping, bearing the seed for sowing, shall come home
with shouts of joy, bringing his sheaves with him.
Also see these: http://www.openbible.info/topics/joy
So the concept of a Christian always suffering is not the Lord's whole picture.
Rather the Christian life is suffering and joy, in parallel, then we pick which one to focus our attention on.
Another very important aspect is to realize how personality and brain disposition effects spiritual and religious interpretation. Studies show that highly sensitive people are more likely to feel they must surrender all for the sake of Christ, including happiness, jobs, money, self confidence, etc.
For a very good read and study of this see:
The Highly Sensitive Person: by Elaine N. Aron, Ph.D.
Joel Osteen is a preacher who actually only focus on the positive parts of God, which is why he gets a lot of heat, but his messages are still true and powerful. For example, see his sermon on holding onto joy.
While he is in the category of Biblical inspiration, he can be a necessity to a complete and whole Christian walk. see his blog for more info:
It is also important to notice that the reality of this philosophy is followed by the #1 biggest church in America and is an specific example of these concepts supported by scripture - of joy, happiness, promotion, health and strength as a Christian - while still acknowledging the suffering.
Also see: Nehemiah 8:10
for the joy of the Lord is your strength;
to rejoice, as the Lord commanded them on such days as these, was a means both of increasing their bodily strength and their inward strength, and of fitting them the more to perform their duty to God and men with cheerfulness, which sorrow and heaviness made unfit for; and the joy which has the Lord for its object, and comes from him, is the cause of renewing spiritual strength, so as to run and not be weary, walk and not faint, in the ways of God.