When I went vegan for a couple of months (it was an experiement that I didn't expect to last, especially after a trip to France), I allowed myself to be flexible about it. I made up my mind to eat meat and dairy once every couple of weeks, so I didn't lose my intolerance to it. That usually occurred when I was visiting friends or somebody else was cooking, so I never had to request a special diet. I still learned a lot and expanded my food reperatoire, so it wasn't a wasted experience in the least.