In my insurance business my customers always like to ask about guaranteed returns. In some instances I can show them that: a certain death benefit, or money pay outs for investments. But the best financial returns lie in the market, and so I give them the choice of what they think best.
The Book of Ecclesiastes also is about choices, and guarantees. The Teacher of the book tells us that this life is a "vapor, or smoke". If we chase after the desires of this world: wealth, pleasures, sex, then we chase the wind in terms of permanence. Instead, he advocates for enjoying the simple things: a good meal, time with family, proper rest.
Oh, and he also advocates for something else too: Serving God with reverence and respect. For he knows that we all die as the great equalizer, and then we will stand before God and give an account for what we have done.
But here is a Guarantee that you can take to the bank! Jesus told His followers: "you trust in God, trust also in Me. In my Father's house are many rooms, and I go to prepare a place for YOU. That where I am, YOU will be also." Friends, now that is a Guarantee that you can live...... and die with!