I was trying to decide between Bio, Chem, and Psych. I'm not super into math, so I was hesitant about choosing a math-heavy major. But yet, I decided on Chemistry. I have a few reasons:
1) I think it's really interesting, especially organic chem and biochem. There is a large focus on drug design and interactions at my school, and I found that fascinating. Our bio program is much more plant focused, so chemistry is really more closely related to medicine here.
2) I feel more challenged in my chem classes than any others, but not so challenged that I can't do well in the courses. They are definitely hard work -- I find that a rewarding aspect of getting a good education. I want to build a work ethic and get used to challenging material. That was really important to me, even though I tried to rationalize that attitude away ("you might get higher grades in bio/psych!" or "more work means more stress!"). I just couldn't shake the necessity to surround myself with something that wasn't naturally easy for me.
3) Kind of related to 2, but I feel proud of being a chem major. When I was still unsure, I pretended to have made my choice, and spent a week telling people I was a chem major and another week telling people I was a psych major and another week telling people I was a bio major. I felt a lot more happy and confident and proud of myself when I told people I was chem, and felt kind of generic and ashamed when I told people I was bio or chem (even though both are great majors, not saying anything against them! But they are huge majors in my school, known for being kind of easy). It wasn't what other people thought of my major, it was what I thought and felt about it. I think that, at the end of the day, this was the biggest factor in my decision.
Good luck OP!