7) Use vitamins & supplements wisely!

I am not big on vitamins and other nutritional supplements. Several large-scale studies have failed to show any benefit of taking nutritional supplements, or have even shown some adverse effects . More importantly, you can get all nutrients from healthy food. So, I don't see why you should spend your money on such supplements. Big companies sometimes imply in their advertisements like that vitamins are natural, and hence safe to take. However, high amounts of some vitamins can be dangerous. For example, high doses of vitamin D can lead to kidney conditions. 

Having said this, nutritional supplements are absolutely necessary if you suffer from vitamin or iron deficiency. I advise to check this out with your local doctor. Your doctor can request a blood test for vitamins, iron, and electrolytes. There is some evidence that vitamin D deficiency is related to depression and poor cognitive function . Low iron can lead to low blood (anaemia) which shows itself with fatigue and low mood.    

Finally, research studies have found some evidence about the benefit of fish oil in brain development and mental illnesses . Fish oil contains Omega 3 fatty acids that might be effective in treatment of depression .  The best way is to include fish (such as salmon, trout, and tuna) in your diet and have them at least twice a week. You may consider taking fish oil supplement (1 gram a day) if you don't eat seafood regularly. Please be aware that some of the fish oil brands in the market might not have the right ingredient; i.e. may not be purely made of eicosapentaenoic acid (EPA) .