Van der Sar confirmed on Thursday that he would retire at the end of the season, bringing an end to a stellar 20-year career.
"I don't see motivation until the end of the season being a problem at all," he said.
"There was a point last year when it was four degrees and the rain was pouring down. Ben Foster asked me whether I still wanted to do it in such rubbish weather. I said I loved it.
"That is still the case. I had a calf injury just after Christmas and was not able to go outside for 12 days. The only time I went outside was to get from the training building to the car, and then from the car to the house.
"After 12 days I wanted to go outside. That feeling will always be there. I want to train and I want to contribute to a team that deserves to win something."