I had trained for 13 years, then took off for 4 years (primarily due to ice hockey related injuries). I then returned to the dojo (the best decision I made). I've now been back training for close to 3 years. When I did come back, I was a bit 'rusty', but you will be amazed how fast the 'body' remembers...just take it slow....
...I was more frustrated about how long it took me to fold my hakama after the 4 year lay-off, than my technique...