Hi Mikeyy109,

First of all, I don't believe that some people just can't do it - in fact I know several people that believed so until they had one. Anyway, having a negative attitude towards LDing won't make it easier to achieve, only harder.
About dream recall, it's something that fluctuates naturally. For example, my recall goes from between 8 full to 2 incomplete dreams, with the average of about 4-5 (after a long history of practicing). So it's totally normal to have several days with no recall in your stage of practice. Some time ago I posted here my tips about increasing recall, so check them out - maybe one or two might end up helpful:

Tips about recall at the last reply (#12)

Either way, I like to compare LDing to things like building muscles, trying to learn a new language, or trying to lose weight - in all of these examples, the most counter-productive thing that can happen is getting stressed or anxious about seeing little to no progress. Also, you simply can't expect results in one day or even a week and even after a month results might be smaller than anticipated. It's like deciding to just stop eating one day to lose weight - not only this won't cause weight lose, it will most likely make you sick and create stress about not being able to lose weight. And after a couple of days, the person trying this is likely to give up. Same here - always stay positive and know that your progress will lag a week or a month from your practice. Even if you're doing everything right - results will start showing up quite some time later. So just stay consistent, and patient, and don't over-do things in the hopes to speed things up - this only leads to more stress.

Also, these dietary improvements and exercise are great of course, but I'm not sure how big of an impact they have on LDing if any... Also, just so you know many recent studies found plenty of benefits in a moderate consumption of tea, coffee, and dark chocolate.