Hello, There are numerous reason for sexual dysfunction. Do you have morning erections? If yes than you might just benefit with psychological measures. Yes smoking do affect your sexual life. Its better to stop it for a healthy life. If tried leaving on own you may face withdrawal symptoms. There are various detoxification treatment available with high success rate.

There are many reasons for sexual dysfunction. Smoking alone is rarely the sole reason for your problems.

more history is required. could be other reasons as well. consult with me or any psychologist for same.

U might be very anxious , check Ur breathing if Ur breathing is fast try to slow down breathing ,do some exercise  and play some games relax Ur mind .your sex will improve