Depending on your gender & obligations, you say it 1-3 times every day of your life.
It's important to say it with kavanah (heartfelt focus).
But what does it mean exactly?
As always, there is a lot to say about such a fundamental blessing.
In Strive for Truth, Volume 2, Part 3, Torah: Inward & Outward, Rav Eliyahu Dessler notes that any attachment to external matters tends to diminish one's inner life.
For example, Rav Simcha Zissel refrained from revealing to others mussar certain insights as long as those insights held the power to affect his own heart.
Telling others releases the "pressure" in one's own heart, whether for better or for worse.
For example, relating your troubles to a sympathetic person can relieve the pressure of these worries.
People who write poetry or do some form of journaling discover this same relief.
But relating certain Torah insights or mystical truths sometimes dims the spiritual light for the one speaking of it.
Many writers discover than when they speak or write to others about what they want to write , they no longer feel the same "oomph" to write about it.
Other writers note that if an idea faces severe criticism, they lose the passion to write about it, no matter how good the idea & how wrong the criticism.
Speaking about a new spiritual practice you wish to take on sometimes has the counter-effect of diminishing your passion for it — especially if your listener is dismissive, discouraging, scornful, or mocking regarding the practice.
Yet Avraham Avinu received a special chessed from Hashem.
Hashem enabled Avraham Avinu to maintain constant contact with people far below his level, in order to bestow upon them acts of kindness, without them influencing Avraham in any way.
Avraham Avinu never lost even a millimeter of his lofty level.
Likewise, Hashem enabled Avraham Avinu to teach others, to reveal all sorts of insights, without ever diminishing his own passion or dimming his own spiritual light.
In other words, sharing his innerness with others never released the "pressure" or diminished his rich inner life one iota.
May Hashem be such a shield for us too.