…give diligence to make your calling and election sure… – 2 Peter 1:10

We then, as workers together with Him, beseech you also that ye receive not the grace of God in vain. – 2 Corinthians 6:1

There is one thought which should not leave us when talking about times and seasons, namely, that now, now, just now, this present flying moment, that second which is being recorded by the ticking of yonder clock, is the only time which we have to work with. I can do nothing with the days that are past, I can do nothing with the days (that are) future-yet I reach out towards them-but I cannot improve them. The past and future are fields far beyond the reach of my culture. I can neither plough nor sow the future, nor can I prune and correct the past. For practical purposes, the only time I have is that which is just now passing. Did I say I had it? While I said I had it, it is gone, like the meteor which dashes adown the sky, or the eagle which flies afar, or the swift ships which disappear beyond the horizon.

Time present is the only time I may ever have. Ere any future shall have become present, I may be merged in eternity. As far as I know, this day may be the end of my life’s career, and when yonder sun sinks to his rest, I may sink to my rest also, so far as time is concerned. If there be more time allotted to me, yet it will never come to me in any other guise and form than as time present. I call it future now, but when I get, say, to 1866, or 1880, it will be just like to these moments, it will be to me present then; and consequently, for practical purposes, however much we may speculate upon the past or the future, the present moment is the only time we have, may have, or ever can have; and it becomes important that all our thoughts should be centered upon it, if we would make our calling and election sure. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0603.cfm