Thank you for your question, which in spite of its brevity brings up a lot of hard issues. I won't try to answer it directly, but just add a few considerations:
1. Considering one's life to be meaningless doesn't show that it is. It may contain sources of meaning that one has not yet appreciated or even conceived of. Also, a person's like may have little meaning to *her*, but a lot of meaning to others, such as parents, friends, etc. In that case, it may have more meaning than one thinks.
2. Meaning can take a lot of different forms. People often wonder about "the" meaning of life, and this suggests that for a life to be meaningful, there has to be one big thing that is its meaning. But this is questionable. After all, in principle there could be a lot of different things that give life meaning, and they might not be intertranslatable into each other of commensurable. A walk in a forest on a crisp fall day, holding a lover's hand, appreciating a novel, having a child, all potentially give life meaning, but in quite different ways. I don't see that they have to be anything more than that.
3. Having a rational reason for doing something is not the same as having a compelling reason to do so. I have a reason to rescue dogs at the local SPCA, but it's more complex to figure out whether I should do that given other considerations.
4. On the other hand, I don't see that, unless we assume a particular religious perspective according to which you're one of God's creatures and therefore are really "His" property, you are obliged to stay living just because you are alive and well.
5. Perhaps the question then becomes, after taking Meaning off its mountain and looking for it in the small and quotidian places as I mentioned above, it's really true that one is *correct* in considering one's life meaningless. Perhaps you've been looking in the wrong places?