The greatest battles take place in the smallest moments
PAUL DAVID TRIPP
There's a lot of truth in that for battles of every kind.
I know from personal experience that one does not work one night and discover that they are have suddenly put on weight. It is through small acts of bad eating choices and then bang, you have put on weight. And what is challenging is that those battles are difficult to win because they are repeated often and seem so inconsequential in isolation.
I have also found that areas where it is most difficult to be a light for Christ is in day by day faithful discipline. For example, it is easy to do an evangelism event, but much harder to know your neighbours. It is easy to pray for world peace but harder to greet that colleague who says nasty things. It is easier to give money to foreign missions but much harder to spend 10 minutes with a homeless person down the road.
The challenge of Christian living is to allow God to be God in these smallest moments.