Lost its ok this is a reality we all have to face eventually. You asked and he gave you the answer. I too have this fear of the end, but I have some what figured out a way not to let it ruin my time now by NOT concentrating on that. He said you still have a lot of time together. He even talked about how that would look in the future by tapering down...but that's it is in the future..not now. Concentrate on today and getting better , cross that bridge when you get there. Don't let the future ruin your NOW. If you concentrate on the end of the trip, you miss the experience of the journey. I know its hard, believe me. It will feel better if your thoughts stay in the moment.