When we go to Heaven, we will not weep because we missed out on doing some of the thing which God through Christ had purposed us to do.
It has nothing to do with us, for in the end it has never been about us, but about Him:
"15Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him. 16For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world. 17And the world passeth away, and the lust thereof: but he that doeth the will of God abideth for ever. " (1 John 2: 15-17)
In the Book of Revelation, one of the elders tells John why he should not cry:
"5And one of the elders saith unto me, Weep not: behold, the Lion of the tribe of Juda, the Root of David, hath prevailed to open the book, and to loose the seven seals thereof." (Revelation 5: 5)
In fact, the Book of Revelation does depict (and predict) what people will do in heaven:
"9After this I beheld, and, lo, a great multitude, which no man could number, of all nations, and kindreds, and people, and tongues, stood before the throne, and before the Lamb, clothed with white robes, and palms in their hands; 10And cried with a loud voice, saying, Salvation to our God which sitteth upon the throne, and unto the Lamb. 11And all the angels stood round about the throne, and about the elders and the four beasts, and fell before the throne on their faces, and worshipped God, 12Saying, Amen: Blessing, and glory, and wisdom, and thanksgiving, and honour, and power, and might, be unto our God for ever and ever. Amen." (Revelation 7: 9-12)
When we are there, we will not be crying because we "missed out" or "we could have done more". We will behold Him who was, is, and ever shall be (Hebrews 13: 8). Our hope to be like Him (1 John 3:1-3) will be realized.
In fact, everything that we have grown to know and believe on in our lives will be fully presented to us:
"And I beheld, and I heard the voice of many angels round about the throne and the beasts and the elders: and the number of them was ten thousand times ten thousand, and thousands of thousands; 12Saying with a loud voice, Worthy is the Lamb that was slain to receive power, and riches, and wisdom, and strength, and honour, and glory, and blessing." (Revelation 5: 11-12)
Paul wrote about this fullness in his epistle to the Corinthians:
"For now we see through a glass, darkly; but then face to face: now I know in part; but then shall I know even as also I am known." (1 Corinthians 13: 12)
Do not worry about your time on earth being for naught. Do not look at yourself, but look at Himself, and Let Him do all the following in your life.