Another way of looking at it is while you are away from your partner on a bussiness trip or war campign Mithra is your partner while you are away.
However the entire modern pagan movement is against the idea of suprresing sexuality. In practical terms becoming celibate is not likely, and becoming celibate is the last thing in my mind, and I am not going to suggest it to any one else either. After all paganism is celebration of life and sexulaity.
What I am suggesting is however a period without any sexual involment. An initiate who is already married would have some problem explaning to their partner night after night that they have a headache. Therefore the time you refrain from sex is going to be decided by you, a week or a year it is left up to you and depending on your circumstances how long a period you abstain.
Before starting the next meditation you need to have fasted (no food or water) since sunset, this is only few hours of darkness during the summer and should be easy enough. Have a wash and dress in clean clothing, remember this is your wedding day!
As with previous meditation more of the physical conditions that resemble the meditation the better. Carrying out this stage in a cave would be great, and have a loaf of expose to sunlight from for a whole day before hand. The piece of bread and the drink would be first thing the initiate had to eat or drink for several hour. The drink could be some sort of herbal tea with some sugar (2).
Also investing in a gold wedding ring would be desirable and by wearing it you will be reminded about Mithra.
Foot Note 1:Technicaly speaking all the energy (food) that we consume does come from the sun through the food chain. Plants absorb the sun light and make sugare, the herbivoiurs eat them and we the plant and the herbivours. Therefore we already have sun in us.
Foot note 2: The drink is based on Homa (soma) as this drink is lost to us, alternatives have to be made, it is up to you how you make it and what you add to it.