Simeon had the promise but during his wait there must have been times that he grew tired or restless. Some may have pitied poor old Simeon, that guy wandering around the temple waiting for the Messiah in his lifetime. Note that he had no following; he wasn't recognized by the high priest.

All he had was the promise. And God answered it unexpectedly one day and made his joy and his life complete. Simeon's experience is a parable to teach us about our own experience God's promise to each of us:

That one day He will come, and in the twinkling of an eye we will all be changed and we will all be with Him in heaven rejoicing forever.
That promise will be fulfilled one day; probably in a way we can't imagine now, a way that will catch us off-guard.

So don't let the mocking, or the indifference of the world deter you from waiting patiently on your lord - He will come and you will be so happy that you waited.

Philippians 2:3–4

Do nothing from selfish ambition or conceit, but in humility count others more significant than yourselves. Let each of you look not only to his own interests, but also to the interests of others.

Isaiah 41:13

"For I, the LORD your God, hold your right hand; it is I who say to you, 'Fear not, I am the one who helps you.'"

1 Peter 5:6–7

Humble yourselves, therefore, under the mighty hand of God so that at the proper time He may exalt you, casting all your anxieties on Him, because He cares for you.

Psalm 94:18–19

When I thought, "My foot slips," Your steadfast love, O LORD, helped me up. When the cares of my heart are many, Your consolations cheer my soul.