Mental strength is necessary for business persons because there are trials that you would see that would want to deter you. But the positivity of your thinking might just be all you need to go aheadMental and emotional health is definitely a very important factor. Businesses can go through ups and downs.. one has to be mentally strong to undergo that without breaking up or giving up. Tough decisions have to be made from time to time in running a business. One needs to have that mental strength to be able to do so.