The Conservative leader said he would create "the responsible society" by rolling back the culture of big government bureaucracy created during Labour's 12 years in power.
And he pledged to take the "tough choices" needed to get Britain out of the recession and pay off record national debts.
In his final conference speech before the election, expected in the spring, Mr Cameron acknowledged that his plans to cut back state spending would be "painful".
But Mr Cameron held out the prospect of better times ahead if voters take the tough Tory medicine.
Insisting he had the character, the temperament and the judgment to be Prime Minister, he told the Manchester conference he was "ready to be tested".
"If we cut big government back, if we move society forward and if we rebuild responsibility, then we can put Britain back on her feet," Mr Cameron said.
"I know that today there aren't many reasons to be cheerful. But there are reasons to believe.
"Yes, it will be a steep climb. But the view from the summit will be worth it."
Mr Cameron said the £175 billion state deficit was nearly twice as big as "when we nearly went bankrupt in the 1970s" adding that Labour were putting the economy at risk by failing to reduce it swiftly.
"The longer we wait for a credible plan, the bigger the bill for our children to pay," he warned. "The longer we wait, the greater the risk to the recovery. The longer we wait, the higher the chance we return to recession."
The "only responsible thing" for politicians to do in the current circumstances was to take "tough choices" like raising the pension age to 66, freezing public sector pay and cutting Whitehall spending, he said.
But he also sought to persuade voters the sacrifice will be worth it by outlining his vision of a better future, telling activists: "If we pull together, come together, work together - we will get through this together."
In a deeply personal speech, Mr Cameron repeatedly said that his politics were driven by what he described as "my DNA: family, community, country".
He recalled the death earlier this year of his son Ivan, which he said had made him question whether he wanted to continue in politics.
And he paid tribute to his wife Samantha, watching from the front row, for "sustaining" him at a time when "it's like the world has stopped turning and the clocks have stopped ticking".
Labour had allowed Britain's economy, society and politics to be "broken" because it relied on big government to sort out problems, rather than trusting individuals and families with responsibility.
"We are not going to solve our problems with bigger government," said Mr Cameron.
"We are going to solve our problems with a stronger society, stronger families, stronger communities, a stronger country. All by rebuilding responsibility.
"Family, community, country. Recognising that what holds society together is responsibility and that the good society is a responsible society.
"That's what I'm about. That's what any government I lead will be about."
There was little new policy in the speech, though Mr Cameron restated existing pledges to preserve the NHS free at the point of use, to give the Bank of England back responsibility for regulating the City and to devolve decision-making powers to doctors and headteachers.
He promised to send more troops to Afghanistan and to equip them properly, and confirmed that former Army chief General Sir Richard Dannatt - a strong critic of the Government's handling of the war - was a candidate for defence minister in a Tory administration.
Mr Cameron delivered a swingeing attack on Labour for failing the poor and vulnerable people it claims to represent, citing the case of Fiona Pilkington, who burnt herself and her daughter to death after police failed to stop bullying by local youths.
He also hit out at the tax and benefit system which he claimed costs a single mother returning to work 96p of every extra pound she earns.
"Who made the poorest poorer? Who left youth unemployment higher? Who made inequality greater?" asked Mr Cameron, jabbing his finger as he spoke.
"No, not the wicked Tories - you, Labour: you're the ones that did this to our society.
"So don't you dare lecture us about poverty. You have failed and it falls to us, the modern Conservative Party, to fight for the poorest who you have let down."
Tony Blair had "wasted his mandate" by ducking big choices, while Gordon Brown had governed by "turning every decision into a political calculation", he said.
A year after being dismissed by Mr Brown as "a novice", Mr Cameron presented himself as ready to be Prime Minister.
"I know that whatever plans you make in Opposition, it's the unpredictable events that come to dominate a government," he said.
"And it's your character, your temperament and your judgment - not your policies and your manifesto - that really make the difference.
"You can never prove you're ready for everything that will come your way as Prime Minister. But you can point to the judgments you've made. And you can learn from the mistakes that others have made.
"So I won't promise things I cannot deliver. But I can look you in the eye and tell you that in a Conservative Britain:
"If you put in the effort to bring in a wage, you will be better off. If you save money your whole life, you'll be rewarded. If you start your own business, we'll be right behind you. If you want to raise a family, we'll support you. If you're frightened, we'll protect you. If you risk your safety to stop a crime, we'll stand by you. If you risk your life to fight for your country, we will honour you.
"Ask me what a Conservative government stands for and the answer is this: we will reward those who take responsibility and care for those who can't."
The 57-minute speech was hailed as "absolutely inspirational" by shadow cabinet member Theresa May, while shadow business secretary Kenneth Clarke said it was "extremely moving at times - a very personal performance".
But Labour's Liam Byrne said Cameron had delivered "a traditional Conservative speech, not a speech of change" and had concealed "the judgment calls he has consistently got wrong".
Dave Prentis, the leader of the Unison union, said Mr Cameron's focus on cuts showed that "the Tories are still stuck in the Thatcher era".
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