"I'm always tired" acknowledges a state of physical fatigue or weariness, which is a common aspect of daily life.
"But never of you" highlights the enduring and unwavering love and appreciation the speaker holds for the person they're addressing. It implies that their feelings for this individual remain strong and unchanging, providing comfort and energy even during times of physical tiredness.
In essence, this quote expresses the idea that genuine love can provide a source of rejuvenation and inspiration, allowing individuals to navigate life's challenges with a sense of warmth and emotional energy, even when they may feel physically tired.