Plaid13

Ok i used to mountain bike alot years ago sometimes 40-50 miles a day but its been about 8 years since i have rode at all. But i have felt like getting back on the bike and riding some. What i need to know is some sort of excercises i can do at home inside now while its still too cold to ride to get myself into a little better shape to be ready for a ride once its nice out. One thing that i noticed when sitting on the bike that i didnt expect is that little bike seat that i used to think was comfortable as hell... now is just flat out painful to sit on. i assume this is because i just dont have the same muscle tone i used to to support myself so its just hard seat right to my tail bone. Any suggestions on what i could do would be great.