External stressors for me, means anything outside the realm of you and your personal thoughts. External stressors could come from family, your fiancé, people you hired, your co-workers, or whatever else it may be. The most stress, for me, came from family members who all wanted different versions of what they thought would be my best wedding. Since it was my wedding, I was actually thinking that maybe I knew what I wanted best? So, I did a lot of tongue biting while smiling and thanking them for their ideas no matter how much I didn't want to listen anymore. At the end of it all, I realized they gave suggestions because they really cared enough about us to speak out.
Maybe you're worried about budget. That's external too. For our wedding, we were initially anticipating 90 people on our guest list which quickly ballooned into 200. We knew this would put us into a financial crunch, but at the same time, they were all close friends and family. So, we agreed to keep it at 200 and we were really careful about our spending. Eventually, I realized, it's not about how much money you spend, but about how much thought you put into the wedding. That's what people notice most. So, we spent more on what was important for us and we cut back on areas that were of less concern. We also paid expenses off gradually throughout the wedding process so that we were never left with huge bills to pay.
Then, there were all the little external details that took a lot of juggling and mediation. We ended up changing our wedding date 3 times, our time of the wedding changed from 2:00pm to 10:00am, and we were very limited in what we could do for cultural reasons. Would you believe it, at the end of all that, we had a great wedding and everyone enjoyed themselves!
My suggestion to you: Be patient. Delegate and give away whatever responsibilities that are not a priority for you. I didn't even choose my bridesmaids' gown or the colour. I only asked that they not choose a morbid colour, or our families would freak, and that they both wear the same colour. The rest was up to them. They chose beautiful gowns, just like I knew they would!