Not some weird fitness program...erase image of guys in smocks doing step ups to a four line beat...but the website:
which accompanies Peter Baker's Introduction to Old English.
Which leads to the observation that since it's got harder to find a course in Old English the possibility of teaching yourself has improved. I did three years at university and learnt very little; the methodology was to throw Sweet's Primer and Reader at us, give us chunks of grammar to memorise and wads of text to translate and to expect something magical to happen. It didn't. Not only was the "teaching" primitive, but I don't remember anyone suggesting the poetry was actually worth reading as poetry. Which is one of the reasons why I'd gone there in the first place.
I suspect I learnt more from Stephen Pollington's First Steps in Old English, which for a small fee (no joke, a small fee) can be converted into a correspondence course. In fact I suspect if you were determined enough you could start knowing nothing, and work through Stephen's book and end up being a competent reader of OE. You'd also be fairly comfortable going the other way, from Modern English to OE.
The Old English Aerobics site is also excellent. An interactive course based on Baker's book. Sadly it's never been finished, but even so, the exercises allow you to review and revise and they never have that look your teacher has when you get the same thing wrong three times in a row. The Anthology, with its point and click dictionary and grammar functions, allow the acquisition of vocabulary without endless page turning in a print dictionary.
In fact, reading the chronicle entry on the Death of William was actually enjoyable.