I have worked professonaly with herbs for decades.I haven`t run a shop in a long time,but I still have the knowledge. The best advice I can give is to beware of salesman.If you think someone is just trying to sell you on something,they probably are.Ask around eventualy you will find someone with real experience.Don`t be afraid to ask questions.If it sounds like bullshit,it probably is.One of the best products I`ve worked with for building someones stamina back is from Switzerland.It is called Floradix formula made by the Floradix company.You can buy it in tablet or liquid,liquid is best by my experience.It is an iron and herb tonic.Herbs take longer to kick in .But after a month or two there should be a noticable difference.Good luck to your friend...OUTLAW