Weir, handed his first job as manager when he replaced Danny Wilson at Bramall Lane in the summer, said after Saturday's defeat at Carlisle that the winning mentality had all but disappeared at the club.
Matty Robson's second-half header clinched Carlisle's first league win of the season and Weir said: "This is a fantastic football club, but I know it needs to be a successful one too.
"There has been a problem here for a number of years in that regard and I have come here to try and make that happen.
"I have my ideas and beliefs about how to achieve success, but like everyone else I will be judged on results."
Weir, whose side have a paltry return of four points from seven matches, added: "When things don't go your way you are obviously disappointed and frustrated and we have had that feeling in our stomach too much this season.
"We have to be open and frank in this situation. That has always been my way and when you are getting beat regularly it becomes even more important.
"I hate the feeling of being a loser and it is something that needs addressing quickly."