"What is the energy of the day?" is a simple request: a symbolic compass for the day starting. A single card in the morning can give a useful tone to the day: a question to keep in mind, a quality to practice, a warning not to ignore.
What the reading reveals
Each Rider-Waite arcanum gives the day a different tone. The Sun announces light and visibility; the Moon invites not to act in confusion; the Magician to use tools you have; the Chariot to pursue a goal; Strength to stay present and calm; the World to celebrate fulfillment. Minor cards speak of more specific themes: Cups (emotions), Swords (thoughts), Wands (action), Pentacles (matter).
How to use it in the day
Draw the card in the morning, read the brief meaning, choose a keyword to carry. In the evening, reread the card and notice if you saw it at work in your interactions. It is an attention exercise that, repeated, creates a daily practice of symbolic awareness. Do not read it as fate: it is an invitation.
FAQ
How many cards per day?
Only one. More tend to confuse.
Can I skip days?
Yes. Not an obligation. A too rigid practice becomes counterproductive.
If the card is "negative" do I ruin the day?
No, if you use it as warning. Difficult cards bring useful information.