This is generally not possible due to the production time plus the transit time of sperm which is around 74 days from the time a sperm is being created to when it is ejaculated. Most effects we see after lifestyle changes, a medication is started, or a procedure is performed, are seen at least months later. If a man is thinking about this question because he is preparing to give an important semen sample such as on the day of the egg retrieval during the IVF process, the best advice I can give is to sleep well the night before and do your best to manage any stress or anxiety prior to giving the sample. Meditation, relaxation, or simply enjoying your favorite foods, music, or other activities in the couple hours before giving the sample can help to clear your mind.