O'Toole acrobatically volleyed home a Chris Beardsley cross to snatch all three points, having netted a last-gasp FA Cup winner at Crawley in midweek.
The former Colchester player had earlier confidently converted a 21st-minute penalty, just seconds after the visitors had gone in front courtesy of Lee Brown's own goal.
It is the first time O'Toole has netted 10 times in a season, and Ward said: "John-Joe has an instinct for getting forward at the right time into scoring positions.
"I told him to sit deeper after Chris Beardlsley went on as substitute, but I'm not going to deter him from following his intuition.
"My players are developing a strong mental approach to go with excellent physical fitness and we have come from behind to win for the second time in a week.
"It's such an important result for us. Had we lost we would have been 12 points behind Exeter, but now the gap is six and we can look towards mid-table.
"Whether we deserved it or not I'll leave to others to judge, but we stood firm in the second half when Exeter put us under pressure and that gave us the chance to win."
- Sports & Recreation
- Chris Beardsley