The suggestion for whey protein powder is spot on. I'm not sure why, but I've found that a whey protein powder shake is far more potent boosters of both my mood and focus than even much larger individual doses of 5-htp and l-tyrosine. Also, 30 minutes of vigorous exercise every day. For years my doctor tried to convince me to start exercising again, and I thought it was just sort of a boilerplate doctor suggestion and that what I really needed was a higher dose / more effective anti-depressant / stimulant. As it turns out, in just a couple of weeks of daily exercise, my mood and focus both improved dramatically, and I was able to take less medicine.
Also, 3 grams of some combination of the omega 3 fatty acids DHA & EPA (found in fish oil -- but 3 grams of those acids, not just 3 grams of fish oil) per day for several months stimulates neurogenesis in the hippocampus, which is generally correlated with antidepressant efficacy. It is fairly safe, certainly safer than eating an equivalent amount of fish as mercury is screened out of the fish oil, though it wouldn't be a good idea if you are on blood thinners.