“And there went great multitudes with Him: and He turned, and said unto them,  ‘If any come to Me, and hate not his father, and mother, and wife, and children, and brethren, and sisters, yea, and his own life also, he cannot be My disciple.  And whosoever doth not bear his cross, and come after Me, cannot be My disciple.
For which of you, intending to build a tower, sitteth not down first, and counteth the cost, whether he have sufficient to finish it?  Lest haply, after he hath laid the foundation, and is not able to finish it, all that behold it begin to mock him, saying, ‘This man began to build, and was not able to finish.’  Or what king, going to make war against another king, sitteth not down first, and consulteth whether he be able with ten thousand to meet him that cometh against him with twenty thousand? Or else, while the other is yet a great way off, he sendeth an ambassage, and desireth conditions of peace.  So likewise, whosoever he be of you that forsaketh not all that he hath, he cannot be My disciple.’” Luke 14:25-33  (KJB)

I will give you John Gill’s exposition of verse 28…

For which of you intending to build a tower,…. Taking up a profession of Christ and his Gospel, is like building a tower; which, as a tower, must be laid on a good foundation; not on carnal descent and parentage; nor on a sober and religious education; nor on a civil, moral life and conversation; nor on a bare knowledge of Gospel truths and a flash of affection for them, and the people of God; but upon Christ the sure foundation; and on principles of grace formed by his Spirit, in their hearts: and this, like a tower, is carried very high; not by professing high things, but by living on high amidst a profession; by having the affections set on things above; and by looking down with contempt on things below; and by looking to, and pressing after, the prize of the high calling of God in Christ: the profession of some persons is very low; it arises from low principles, and proceeds on low views, aims, and ends; but where it is right, and well founded, it is like a tower, firm and steady, and is a fortress and bulwark against apostacy. Now what person acting deliberately in such a case as this, and proceeding with intention and design,

sitteth not down first, and counteth the cost, whether he have sufficient to finish it? as every wise man would, who has any thoughts of building a tower, or any other edifice: and so such that have an intention to take up a profession of religion, should sit down and well consider of it; which does not imply, that persons should delay making a profession, on whom it is incumbent; but that this should be done with thoughtfulness, care, and prudence: it should be considered on what foundation a man is going to build: whether the work of grace is truly wrought upon his soul; what be the nature and use of Gospel ordinances; with what views he takes up a profession, and submits to ordinances; what the church and minister are, he intends to walk with; and what the charge and cost of a profession; for such a work is chargeable and costly, and should be thought of and considered, whether he is able to bear it: for he will be called to self-denial; and must expect to suffer the loss of the favour of carnal relations and friends; and to be exposed to the scorn and rage of the world; a cross must be took up and bore; and great grace and strength are requisite to all this.