I am Arminian in theology, not because I feel any particular bond or loyalty to James Arminius, but because I believe the Bible clearly teaches that salvation is not accomplished without, and is predicated upon, the the conscious choice of the saved. It's not that God isn't involved nor even providing the impetus toward salvation, but that belief in Christ is a response made by, not for, the saved. It's a question of personal faith, and, given the wooing of the Holy Spirit, it is possible for everyone.
Believing in Jesus is, in fact, the work that God requires of us. As Mark Knopfler might say, "that ain't workin'!" But that is the way we do it! Faith is not the product of sweat and toil, nor the fruit of planning and vision. It's a response to a circumstance, a reaction to a stimulus. The word of the Lord (stimulus) came to Abraham, faith was his response, righteousness his reward. Jesus died for our sins and rose from the dead on the third day for our justification (circumstance), faith is the reaction of the saved, eternal life is the repercussion. Where's the work in all this?
The answer is that it is excluded. The work was done by God, we only respond to it. It is by grace that we are saved, through faith, not of works so that no one can boast. Jesus was being tongue in cheek when he answered that question that way that day. It must have struck a perplexing note in his hearers--"what kind of work is that?" they might have asked themselves. That's just it, it isn't one, and that is what the Lord wanted to highlight.