Don't be stressed out.

One of the greatest killers of a great life is undue stress. A certain amount of stress can serve as motivation to study for a test or work hard at closing a contract, but we must learn to entrust to God and others events and attitudes which are beyond our control.
The Serenity Prayer is a beautiful prayer which keeps the balance of this perspective:

God grant me the serenity to accept the things I cannot change, courage to change the things I can, and the wisdom to know the difference.

Two Bible passages that encourage us to entrust our lives to God are Proverbs 3:5-6 and Philippians 4:6-7.

Prov 3:5-6 Trust in the Lord with all your heart, And do not lean on your own understanding. In all your ways acknowledge Him, And He will make your paths straight. NASB

Phil 4:6-7 Be anxious for nothing, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all comprehension, shall guard your hearts and your minds in Christ Jesus. NASB

These verses remind us to leave our concerns and worries before the throne of Almighty God. In His sovereignty and love, we trust that all things will work out for the good, to those who love God and are called according to His purposes (Romans 8:28). This does not mean life necessarily will be easy, but we can have peace in the midst of the difficulties we face, and be thankful when we have a modecum of success.

Two other sayings help us keep this balance:

Work as if everything depends on you, pray as if everything depends on God.

Don't sweat the small stuff!

All that we might have a great life filled with peace, not stress!