...but why are you doing it?
The "random act kindness" concept was kind of neat, but sad, too, in a self-limiting kind of way, rather like the Boy Scout business of "do a Good Deed daily". Is there not sufficient need or opportunity to do more than merely one? ( This reminds me of a virtually unknown cartoon from Terrytoons, "Good Deed Daly", a happy little Boy Scout from 1955. This is virtually all to be found online about it. Good deeds, even with Unintended Consequences, are apparently poor cartoon fare) Perhaps the good feelings one has upon Doing such a Deed will encourage one to do another, then another, until your whole day is spent satisfy the Good Deed jones one develops. "C'mon lady, lemme mow your lawn again..you KNOW I'm good for it!"
Motivation comes into the picture. Paul says in Romans that if you do good to your enemy, you heap coals of fire on his head. However, this is a result; it is not intended to be the motivation: "Here is a cup of cold water in Jesus' name...feel the BURN, jerk."
Perception is another thing. One thing I have noted before is that passive-aggressive behavior has become de rigueur in the Christian community. I can't hit you, but by goo I can sure annoy you. Unfortunately, this colors the whole spectrum of good deeds done by a believer. I have noted in some blog comment threads elsewhere that when Bible-believers and non-believers get at loggerheads over Issues such as abortion or Intelligent Design, after things heat up, often the believer says summat like "This is really getting us nowhere. I'll pray for you." Now, nine times out of ten, this is likely a sincere statement of intent, that I shall intercede with the Almighty for good things for you, or for clarity of thought. But the perception is: "I'm SO over you, better than you, and Jesus may love you, but he doesn't like you very much!". Unfortunately from what I see in the Blog-o-VerseTM
and in REAL life, the perception may not be far off the mark at times.
Some things come to mind: first, the Scripture says: let not your good be evil spoken of. Consciously avoid even the perception of emotional taint. As far as is possible with you, be at peace with all. Jesus said to not parade the good things that we do before others...
Matthew 6:2, "Therefore when you do your alms, do not sound a trumpet before you, as the hypocrites do in the synagogues and in the streets, that they may have glory of men. Truly I say to you, They have their reward."
The point is that the DOING is the important thing, not the TELLING. If you are going to pray for someone- especially someone with whom you are at odds- just do it. Don't announce it. Don't do a Pharisee dance. Just do it. There is no opportunity to be misinterpreted, and every opportunity for God to do His work.