Asceticism, self-denial in a narrow way towards righteousness. "Righteous conduct."

According as God hath chosen us in him....

we should be holy and without blame before Him, in love....

-Ephesians 1:4

Paul is making the case for righteousness in personal conduct, being "without blame"--that this is a way of honoring God everyday.

Meats for the belly, and the belly for meats:

but God shall destroy both it and them.

Now the body is not for fornication, but for the Lord;

and the Lord for the body.

-1 Corinthians 6:13

We see the sentiment extended to diet, or at diet as a metaphor, and sexual abstinence, ascetism or complete self-denial, as a neat way of avoiding any potential blameful situation.  Of course, the easiest manner of never being in a sexually impure or compromising situation is to entirely avoid fornication of any sort.

We see the concept of "lifestyle Christians" mentioned around, used as a condemnation of people who see the faith as a routine or program instead of faith, awe and love.  I've seen various sorts, on my own, and even from time to time probably have tried it in my own life.  

There are people that live quite, peaceful lives, never reaching out to others.  In comparable silence, they observe their diet, their personal dress, and other aspects through the lens of a laymen's asceticism/monasticism.

I offer no particular condemnation; if those aspects that they are so concerned about dictate so much attention and focus, they should observe it.  In fact, the rigid enterprise of trying to attain righteousness on Earth would seem to require a lot of effort for "old sinner's saved by Grace".

It takes a lot of effort, a mindful kind of self-appraisal, constantly, to purge sinful, destructive things from one's life-

-Christ said it was a Narrow Way, like lives of service in the secular world, requiring a devotion and selflessness that often goes in contrary to our natural instincts.

However--

we've got a little extra something to hold to, as we attempt or endeavor in our daily lives:

...he hath abounded toward us in all wisdom and prudence;

having made known unto us the mystery of His will...according to his purpose..

Ephesians 1:8-9

We have the love of God, and the example of Christ-

-how much they would do for us, how much they did for all so long, ago.