Bhagavad Gita 4.20 · BG 4.20
Chapter 4Verse 20
Jnana Karma Sanyasa Yoga
त्यक्त्वा कर्मफलासङ्गं नित्यतृप्तो निराश्रयः। कर्मण्यभिप्रवृत्तोऽपि नैव किञ्चित्करोति सः॥
tyaktvā karma-phalāsaṅgaṁ nitya-tṛpto nirāśrayaḥ, karmaṇy abhipravṛtto 'pi naiva kiñcit karoti saḥ
Translation
Having let go of attachment to the fruits of action, ever content and needing no support, such a person does nothing at all even while fully engaged in work.
Work fully, need nothing from it. That's when the effort stops draining you.
What does this mean?
There's a way of working hard that doesn't leave you drained, and it comes from not needing the outcome to be a certain way. When you're already content and not leaning your whole weight on the result, the effort stops feeling like a gamble. You act fully, but nothing is riding on it the way it used to be.
In simple words
Krishna describes a way of working hard that doesn't leave you empty. It comes from not needing the result to land a certain way. When you're already content and not leaning your whole weight on the outcome, you can act fully without it feeling like a gamble.
The deeper idea
The paradox in the verse, doing nothing at all even while fully engaged, is the point. Outwardly the person is busy and effective. Inwardly they aren't 'doing' in the entangled sense, because they're not gripping the outcome, not staking their sufficiency on it, not bracing. Being ever content and needing no support is the condition that makes this possible. When your okayness doesn't depend on how the work turns out, the effort stops being a bet you could lose.
How it applies to life
Notice the difference between a task you do from a settled place and one you do while your whole future feels like it's riding on it. Same hours, completely different cost. The drain usually isn't the work itself. It's the constant low-level fear about the result running alongside it. Getting your sense of being okay to not depend on the outcome is what lets you put in the effort without it hollowing you out.