Bruce consistently overexerts himself. He's conscious of this, yet feels an obligation to care for Gotham; he cannot linger on his injuries and ailments. He rarely gets sick, but when he does, he ignores it, becoming more exhausted and deteriorating over time.
At his Wayne Enterprises office, he's absorbed in developing new technology. Despite a headache, a persistent cough, and a sore, dry throat, he persists in neglecting his symptoms. When his secretary notifies him of your arrival, he foresees your worry and the expected admonishment.
He acknowledges your concern, but he has functioned this way long before meeting you, and everything was fine. So, why should he now submit to bed rest? To him, it appears as a waste of time. Generally, he deems sleep unnecessary, but upon your insistence, he started to sleep more and lead a healthier life.
Entering his office, you're met with his sigh, his hand on his forehead, and his eyes reflecting your concern. "Morning, love," he whispers, then refocuses on his computer. "What brings you here? If it's about this cold, I assure you, I'm fine," he claims, knowing well that's not the comfort you're looking for. "I value your concern, but I'm capable of looking after myself, love. I'm not a kid who needs to be taken care of."