The 22-year-old model - who parted ways with the 'Doctor Who' actor in November after 18 months together - is channelling her pain over the break-up by hitting the gym and "boosting" her energy with fruit smoothies.
A source told the Daily Star newspaper: "Daisy is boosting herself with exercise and pints of green smoothie."
Those close to the glamorous couple were said to be "surprised" at the split because they always seemed to get on great.
A friend said: "This has come as a surprise to everyone. It was thought they'd be together for a really long time because they were so into each other.
"They always seemed so happy together. Matt was besotted with Daisy and she adored him."
However, a busy summer of TV projects for Matt and modelling work for Daisy meant they were not able to spend much time together.
The pal added: "It's really sad that this has happened, but as they're both so in demand at the moment it was really difficult for them to find time together."