Some might say that things like Bible study, worshiping, preaching, administering the sacraments, prayer, evangelism, etc., are merely means to an end. However, that seems to me to be an unbiblical and pragmatic-focused approach.
When we are commanded to do these things, and when God has given us specific directions for these things, it is wrong for us to place conditions upon that obedience (ie, if I tithe over and above what is required, then I should get rich. Or if I properly evangelize 100 people, then 50 should be saved.)
Placing our eyes on the outcome of our obedience supercedes God's sovereignty, the power of the Holy Spirit working, and the Lord's rule over all of life.
Secondly, since the chief end of man is to glorify God and enjoy Him forever, then all that we do should be done to the glory of God. In the early 90's I remember telling one of my supervisors that my job was a means to an end, not an end in itself. What I was communicating is that I could take it or leave it, that my job was not a priority. I believe this is also unbiblical. We should do our work and serve our employers as if we were specifically doing that labor for the Lord himself. In fact, the reformed faith has a long tradition of placing a high regard on vocation (the Protestant work ethic).
Therefore, everything that we are doing is an end and not merely a means to an end -- the end being the glory of God. Thus, by obeying a specific command of God for His Church, we are not performing "a means to an end," but rather we are manifesting the end in itself -- the Glory of God in and through the Church.