When I look back at my days as a white belt  I remember how tough the training was.   My lungs would burn because I wasnt used to the endurance it required to train, my muscles would burn from not having learned yet when and where to use the proper amount of force , and my arms, legs and throat would be just beat up from getting tapped all the time by the higher ranked belts.
Back then I never worried about being tapped, it was just a fact of life that when I walked through those doors I was getting tapped , there realy was no stress, just alot of muscle aches.   As time went on though, as with every Bjj guy who trains long enough, the tide began to turn in my favor and I was slowly but surely tapping out people, and as more time went on I started to catch the guys that used to always tap me.
It was right about this time, when I got my blue belt, that I started noticing a peculiar thing.   Some of the guys who had been blue belts before me, and some of the higher ranked guys werent as eager to train with me as much as they used to be, not that they were afraid to roll with me, alot of them could still on average beat me, but it seemed like I was practically selling them on training with me.    I’d hear the usual excuses like “Im just training light today” or “I just tweeked my neck, ask scott if he wants to train”.   The sudden injury seemed to be the most popular reason why people couldnt train, but about 20 minutes later I’d see the same guy rolling with someone else at full speed.   His injury had seemed to miraculously heal.
What this all really boils down to is that almost everyone above white belt hates to tap, but whats an even more  dreaded scenario to these same people is to get tapped by a person of lower rank and this type of attitude can really hinder not only your preformance on the mat, but true advancement in Bjj.
I believe it was Rigan Machado who was once consuling one of his newly appointed black belts who was so stressed about be caught in a submission by anybody of lower rank than him to which Rigan laughed and said “everyone taps my friend!”
Tapping is part of everyday life on the mat in jiu jitsu, it is one of the greatest assets to training in Bjj there is.   Tapping tells you what you need to work on, shows you where your game is weak and also, when you make the person tap, where you are strong.   Believe me, when I started going up in rank I completely fell into the “I cant get tapped ” mentality, until a black belt said to me “How are you ever going to get better if you always play to win and not open up your game”, and by “opening up your game” he meant engaging in problem spots like passing the guard, cross sides, the back position, etc…
Its only when you start allowing your self to fail that you can realx and learn from these mistakes to improve and win.
My suggestion is to always seek out the person you least like to train with, the one that would make you scream inside if he or she tapped you, and after a litle ego bruising you will start to notice how much you not only improve your physical game but also your mental game as well.