Gotta toss my hat in this ring, boys...
What I was relying on was Acai from Walmart. Worked effing great. (The Vitamin Shoppe version of Acai worked wonders for staying awake on no sleep but that's another story.)
Then, I suffered a back injury early this year and caused all kinds of problems with numbness in ALL extremities. During my ongoing recovery employing chiropractic, acupuncture and various exercises, I SLOWLY regained sexual function. Unfortunately, Walmart changed their Acai formulation and I was back to my pre-injury dilemma.
What works FOR ME now is simply a good serving of ...drumroll, please... watermelon. Yup, just that simple. As others have noted, nitric acid is a key and watermelon has it.
Of course, eliminating testosterone killers is a good idea as well as reducing alcohol consumption, getting enough sleep, losing weight and exercising with HEAVY WEIGHTS. Also cut out sugar late last year before my injury but not sure if that has any bearing on this.
Finally, and possibly second most significance, is that I credit Kegel exercises for strengthening the pelvic floor. Don't laugh. It works, it's free and it's safe.
Have fun, men, and stay safe and healthy.