Best energy boosting product on the market?

There are legitimately thousands out there now and the claims they make are huge. I have recently started back working out for about eight weeks now and getting to where my recovery time is getting relatively short and approaching my peak. However, I still feel tired all the time. In college, when I hit the gym regularly my energy levels spiked. I am only 32 - I am hitting the gym, increasing the weights, decreasing fat, but my energy levels still feel low. The only differences I know exist physically are increased age and increased stress levels (jobs > college life).

With all that being said, what is the best thing out there to increase energy levels? Supplements, diet plans, or just keep grinding and let my body get the routine down...