Psalm 37 begins with “Do not fret…” then is quickly followed by “Trust in the LORD and do good.”
(NASB) Psalm 37:3b “…Dwell in the land and cultivate faithfulness.”

Aren’t we to live each day where we are and cultivate, nurture…faithfulness?
One facet of the fruit of the Spirit is ‘faithfulness’.  (Galatians 5:22)

God is like a shepherd – He tends His flock…He gathers lambs in His arms to carry them…He carries them close to His heart.
(NASB) Isaiah 40:11 “Like a shepherd He will tend His flock,
In His arm He will gather the lambs
And carry them in His bosom…”

Are you in circumstances in which you would welcome the Shepherd to gather you in His arms and carry you close to His heart?  Knowing the Shepherd as your Savior and LORD…is to be in His presence – even in the hard places of life.
The Shepherd is faithful to His flock.

(Amplified) Psalm 37:3
According to the Amplified Version of Psalm 37:3 We are to lean on the LORD, relying on Him with confidence = Trust.
And as we are actively trusting in Him we are to do good.
This is how we are to live in the land and we are to eat, feed and cultivate His faithfulness. (Being spiritually nurtured is essential in the life of the follower of Christ).

(NASB) 1 Peter 5:6-7 “Therefore humble yourselves under the mighty hand of God, that He may exalt you at the proper time,
7 casting all your anxiety on Him, because He cares for you.”