The phrase "Have a wonderful day" is a friendly and caring sentiment, expressing the desire for the recipient to have a great day filled with happiness and positivity.
The second part, "Know that I'll be thinking about you every second," reveals the depth of the speaker's feelings. It indicates that the person is constantly on their mind, and their thoughts are consumed by the recipient throughout the day. This highlights a strong emotional connection and a sense of longing.
In summary, this message combines well wishes for a great day with a heartfelt declaration of affection. It expresses the idea that the recipient holds a special place in the speaker's thoughts and heart, making their day brighter just by being in their thoughts.