I am 27 years old man, unmarried but sexually active. For last year or so, I am having weak erection, and at times even unable to get erections while trying to have intercourse with my partner. For past one weak I am observing that my erections are only partial, while masturbating, I ejaculate before getting fully erect. Even nocturnal erections are very feeble. There is no pain or any visible signs of damage on the penis or testicles. I have been smoking occasionally for years, and also been a chronic masturbater throughout my youth. Could that be a problem? Although I am a professional athlete, extremely physically fit, and have been exercising for years.