If you force yourself to continuously do good, there will come a time when you can't find a way to bring goodness out of something, from this frustration you will become angry and contradict the very thing your trying to achieve.
You just have to be realistic and understand that if you can't bring the goodness out of something, maybe it isn't something you are or are not doing. Maybe there just isn't any good to come out of it. But as long as you know you've done what you can, that should be satisfying on it's own.
I do not think so because I follow the concept that one's own problems shrink in comparison to others. One must always help others to the furthest extent that they are able. If such a philosophy becomes so draining on a person that they are no longer able to do this effectively then they should take a break before going out and doing it again.