2. Weight Train
Exercise can greatly increase your testosterone levels,particularly weight training. One study found that men had a significant testosterone-raising response to weight lifting. 
Do not overtrain, though. Overexerting your body without including proper rest can also deplete testosterone levels.
3. Take Your Vitamins and Minerals
Essential nutrients greatly affect your testosterone levels. In particular, zinc and vitamin are shown in studies to positively influence testosterone. 
Zinc can be found in protein-rich foods like meat and fish and leafy greens like spinach. If you decide to supplement with zinc, remember the recommended dietary allowance is 11 mg/day for men. 
Vitamin D is obtained from sun exposure, but many don't get enough. In fact, about 40% of older people in sunny climates don't get enough vitamin D. if you don't get enough sun, you might consider supplementing; the RDA is 600 IU.