God promised Abraham and Sarah a child in their old age, and, despite their worldly attempts to bring about children on their own (possibly motivated by frustration, desperation or fear), God held true to His promise to them. Genesis chapter 21 shows Sarah giving birth to Isacc, with verse 2 specifying that she bore him "at the set time of which God had spoken to him" (NKJV). After being barren for so long, Sarah and Abraham were overjoyed with the blessing of their new baby, and in response to this they named him Isaac, which means "he laughs." Genesis 21:6 records Sarah saying "God has made me laugh, and all who hear will laugh with me" (NKJV). While it must be acknowledged that not all of Abraham and Sarah's actions or decisions were good ones, here we see at the very start of Isaac's life that they are properly responding to this blessing; not only rejoicing personally, but also glorifying God, recognizing His might and power at work, and making it known that He is the author and source of their happiness, as opposed to glorifying themselves or their own efforts.
We can remember earlier that when God spoke of His plan to bless Abraham and Sarah with a child, in Genesis 18:12, that she laughed then as well at how impossible it must have sounded to her, later denying it out of fear when God asked. Despite how impossible things may seem to us today, we have this reminder from God Himself in 18:14 asking, "Is anything too hard for the Lord?" (NKJV). We already know the answer: that all things are within God's power, and that He is working all things out according to His plan, at His time- the story of Isaac shows this clearly.
Isaac was a major part of God's plan, despite the fact that he was not always a good or noble person; he seemed to play favorites with his sons, loving Esau more than Jacob in chapter 25:28, and at times he knowingly lied or compromised under pressure, deceiving Abimelech about his wife (as shown in 26:6-11) for fear of men. However, despite these mistakes, he was one of those under the covenant that God had made, and as such, Isaac was still loved by God; his birth was a clear descendant of Abraham and a step in God's plan. Throughout his life Isaac demonstrated great trust and patience toward those who had authority over him; he deferred to his father both at the sacrificial site where the ram was provided, and at the arrangement of his marriage to Rebekah, which we clearly see the true hand at work and final authority as God Himself.
Isaac was also patient in not being drawn into surrounding conflicts or costly distractions, being willing to compromise in a positive way; after Genesis 26:16, when he departs from Abimelech and moves into the Valley of Gerar, he chose not to fight or act harshly multiple times when other peoples quarreled with him and his wells that he had re-dug- a lifeline in those times and places; rather than attack rashly, Isaac chose the course of peace and moved on, more than once selecting a peaceful path over a more immediately-gratifying one. After finally digging a well that was kept in peace, he glorified God in chapter 26:22 saying "For now the Lord has made room for us, and we shall be fruitful in the land” (NKJV) - despite his own choices and efforts (not all good) he, like his parents, came to understand that the blessings he received could only have come from God, and he glorified Him in response and joy for everything he saw God had done.
We as readers today can look to Isaac's life as a living example of how, if we patiently wait on God to work on and in us, we will be capable of doing more than we could possibly to do alone, and enjoy far greater blessings and peace than anything we could ever hope to achieve by our own strength or skill alone. We can laugh in happiness and joy, free of care or fear knowing that we're held safely and securely in God's love, that He is working all things out for good in His own time.