在小说《飘》中，斯佳丽遇到挫折时总会想到：“I won’t think of it now.”

下面是结局中的一小部分：

    There was a merciful dullness in her mind now, a dullness that she knew from long experience would soon give way to sharp pain, even as severed tissues, shocked by the surgeon’s knife, have a brief instant of insensibility before their agony begins.

   “I won’t think of it now,” she thought grimly, summoning up her old charm. “I’ll go crazy if I think about losing him now. I’ll think of it tomorrow.”

   “But,” cried her heart, casting aside the charm and beginning to ache, “I can’t let him go！ There must be some way！”

   “I won’t think of it now,” she said again, aloud, trying to push her misery to the back of her mind, trying to find some bulwark against the rising tide of pain. “I’ll—why, I’ll go home to Tara tomorrow,” and her spirits lifted faintly.

我的疑问是：

为什么“I won’t think of it now.”有个now但是却用将来时？

如何理解I won’t think of it now？