Reasonable Service

Rom 12
1  I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.
2  And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
3  For I say, through the grace given unto me, to every man that is among you, not to think of himself more highly than he ought to think; but to think soberly, according as God hath dealt to every man the measure of faith.
4  For as we have many members in one body, and all members have not the same office:
5  So we, being many, are one body in Christ, and every one members one of another.
6  Having then gifts differing according to the grace that is given to us, whether prophecy, let us prophesy according to the proportion of faith;
7  Or ministry, let us wait on our ministering: or he that teacheth, on teaching;
8  Or he that exhorteth, on exhortation: he that giveth, let him do it with simplicity; he that ruleth, with diligence; he that sheweth mercy, with cheerfulness.
9  Let love be without dissimulation. Abhor that which is evil; cleave to that which is good.
10  Be kindly affectioned one to another with brotherly love; in honour preferring one another;
11  Not slothful in business; fervent in spirit; serving the Lord;
12  Rejoicing in hope; patient in tribulation; continuing instant in prayer;
13  Distributing to the necessity of saints; given to hospitality.
14  Bless them which persecute you: bless, and curse not.
15  Rejoice with them that do rejoice, and weep with them that weep.
16  Be of the same mind one toward another. Mind not high things, but condescend to men of low estate. Be not wise in your own conceits.

What is your reasonable service in the Kingdom of Heaven?
To do with joy and humility that which God has gifted you to do.
If you are gifted to prophesy, than do so as God speaks to you, not taking credit nor having pride in your gift, but with an attitude of gratefulness to your Master for having chosen to use you in such an awesome way.
If you are gifted to teach, teach according to how God has taught you. Make no great thing of your wisdom or knowledge of Scripture, nor your understanding of the things of God: for it is God who has allowed you to to possess this insight.
Some are gifted to love: to shared the love of God. If this is where God has given you and extra portion, do so without regard to the person, but with a God-like affection and concern for the soul and spirit -- beyond the outward lovability of the physical person.

When we, as Christians, make full use of our Gifts, to the Glory of God, we are then - and only then - offering up our reasonable [intelligent - "with comprehension"] service.