Trouble working out my Aussie

So I have a 1 year old Aussie who has a ton of energy and I've been having trouble tiring her out. I'll usually take her out in our yard to play fetch, but she gets tired/ bored about 15 minutes into it and just starts sniffing around instead of going for the ball. She seems tired when I take her back inside but then after resting for a little while she's all hyper again. Same thing when I take her running. By the end she's having trouble keeping up but then she'll rest up or take a short nap and we'll be back to square one. The only thing that seems to tire her out for the whole day is playing with other dogs. I used to take her to the dog park a lot but I've stopped doing that as much because I think she picks up some bad habits there and the environment is too unpredictable. Any suggestions?