The DWP accused Green of falsely claiming £42,013 in PIP, but accepted a guilty plea to a sum of £25,244.
She had claimed her arthritis was a lifelong condition that would progressively get worse and said she could not walk for more than five minutes without the crutches.
She also told the DWP she needed help with washing, bathing, dressing, preparing meals and eating and drinking.
Mandy Tobias, from the Crown Prosecution Service, said: “Helen Green pretended she had limited movement, but instead was a regular runner and active in gym classes.
“She did this for her own greed and lined her pockets with fraudulently obtained money.”