I am having a tough time writing the logic for some program in assembly

We're being taught x86 assembly in college, and I understand everything that's happening. I have some basics by having learnt 8085 and it's assembly language. The thing is, I can build the logic for the code in my head, vague ideas like what registers to use, etc. But, I can't for the life of me write the code in assembly. I don't know why, I have tried practicing, I've spent hours on just understanding the code, going through multiple discussions on various forum boards, but to no avail. I just can't write asm code. I always struggle converting str to ascii even though ik the logic extremely well, bcd to hexx block transfer of strings and other stuff like this. Any tips?