Britain has narrowly avoided a double-dip recession but financial forecasters have predicted a struggle for the rest of the year.
Businesses need to stop hoarding cash and start investing, the Ernst & Young ITEM Club has said.
Emergency measures from the Bank of England, European Central Bank and US Federal Reserve were praised by the forecasters, saying that through boosting confidence and stabilising financial markets, the UK has been pulled back from the brink of recession.
UK GDP growth will be a "dismal" 0.4% this year, which is half the 0.8% estimated by the tax and spending watchdog, the Office for Budget Responsibility, before rising to 1.5% in 2013 and 2.6% in 2014.
The UK economy shrank by 0.3% in the final three months of last year and is broadly expected to have just avoided a technical recession by eking out around 0.1% to 0.2% in the first quarter of 2012.
Peter Spencer, chief economic adviser to the Ernst & Young ITEM Club, said the UK will not prosper again until businesses invest stockpiled cash.
He said: "Business investment has picked up nicely in the US but UK companies remain extremely risk averse, which is sapping strength from the economy."
The cash balances of private non-financial companies are worth more than £754 billion, the ITEM Club said, 50% of GDP, but business investment last year only increased by 1.2%.
In contrast to big business, households remain under intense pressure, the ITEM Club said, with private sector companies finding it increasingly difficult to create the jobs to offset losses in the public sector.
Unemployment is expected to approach 9.3% of the UK's total workforce by the middle of next year, with just short of three million people out of work, before beginning to fall back, the ITEM Club said.
Mr Spencer continued: "Households remain under the cosh and UK unemployment is set to go even higher by the end of the year.
"But there is a small glimmer of light at the end of the dole queue. For the first time in years, the gap between wage growth and inflation should start to close, before reversing in 2013."
ITEM forecasts that disposable income will fall by 0.2% in 2012, while consumer spending will increase by 0.8% before accelerating to 1.1% in 2013 as household incomes gradually strengthen.
Elsewhere, the ITEM Club has predicted that the UK's export performance should pick up despite shipments to the eurozone being restrained.
Exports of goods increased by 5.1% in volume terms in 2011, while services were up by 3.9%. The UK is expected to put in a similar performance this year, the ITEM Club said, with exports growing by 4.5% and net exports adding 0.3% to GDP.
Mr Spencer said: "The UK has so far avoided the dreaded double dip, but a lot still hangs in the balance.
"After three business-friendly Budgets and more tax cuts in the pipeline, it is now up to corporates to play their part in the UK's recovery.
"The business community needs to grasp this opportunity quickly or face the consequences after the next general election."