Matthew Henry commenting on what it means to watch and be ready:
To watch implies not only to believe that our Lord will come, but to desire that he would come, to be often thinking of his coming, and always looking for it as sure and near, and the time of it uncertain. To watch for Christ’s coming, is to maintain that gracious temper and disposition of mind which we should be willing that our Lord, when he comes, should find us in. To watch is to be aware of the first notices of his approach, that we may immediately attend his motions, and address ourselves to the duty of meeting him. Watching is supposed to be in the night, which is sleeping time; while we are in this world, it is night with us, and we must take pains to keep ourselves awake.
Be ye also ready. We wake in vain, if we do not get ready. It is not enough to look for such things; but we must therefore give diligence, 2 Pt. 3:11, 14. We have then our Lord to attend upon, and we must have our lamps ready trimmed; a cause to be tried, and we must have our plea ready drawn and signed by our Advocate; a reckoning to make up, and we must have our accounts ready stated and balanced; there is an inheritance which we then hope to enter upon, and we must have ourselves ready, made meet to partake of it, Col. 1:12.
(For) the issue of our Lord’s coming will be very happy and comfortable to those that shall be found ready, but very dismal and dreadful to those that shall not.
Matthew Henry is a card -carrying G.O.A.T. (Greatest Of All Time). If you haven’t ever read his commentary on the whole Bible (yes, the whole thing), you can get it for free online here. You can buy the volumes here.