I've found that vitamin and herbal supplements from health food shops work quite well. They usually do a package labelled for 'men's health' or some such euphemism. The tablets I take have multivitamins, zinc, etc, I also take ginseng. Seems to work, I have more energy than before.
I'm also finding that as I get older, alcohol is having a worse and worse effect on me - testosterone plummets, I get emotional, can't sleep and feel dizzy even after 3 or 4 drinks, whereas in my teens/twenties I used to drink about 7-8 pints of beer and feel fine the next day.