I was late for my flight yesterday,because I wanted to sleep so much that it was hard to get up by myself this morning.And I'll forget this unpleasure thing.
我没能赶上昨天那班航班,因为我太想去睡觉了以至于今天早上很难自己起来.我将会忘记这件不愉快的事情.
好像有点不太通顺 不过按你题目的意思又不让用过去式,只好变成这样了.