Wow... I'm getting old.

It's a disturbing thought, one that usually hits after an unexpected physical challenge — like weaker workouts, slower recovery, or not performing in the bedroom the way you used to.

And though you may not "feel old," you know you don't look or feel like the man you used to be.

The issue? You might not have enough free testosterone

A person's bloodstream contains two types of testosterone: bonded testosterone and free testosterone. Bonded testosterone attaches to molecules in the body and is mostly ineffective. However, free testosterone can enter your cells easily and plays a vital role in libido, strength, stamina, and vitality.

While the market is flooded with questionable options for increasing a man's free testosterone levels, a group of researchers in Boston, Massachusetts have developed a dietary supplement that's different. It triggers the body to increase its levels of free testosterone naturally and safely.

Called Nugenix, the supplement primarily relies on an ingredient called Testofen®, which has been shown in clinical trials to boost free testosterone levels, increase sex drive, and improve libido. Adding to Nugenix's potency are additional key ingredients like zinc and vitamins B12 and B6, which have been shown to improve physical performance and strength, increase drive, and aid in recovery.

Nugenix has no harmful side effects, and has been shown to deliver improvements in strength and endurance in as little as a week. According to studies held in both Irvine, California and Queensland, Australia, users reported greater muscle definition and quicker recovery times, increased sex drive, and feelings of alertness.

Best of all, right now the company that manufacturers Nugenix is giving away samples of the products to qualifying customers who request them online.