Well first of all, as an American citizen we have obligations and responsibilities to our country and communities. So let's begin there, it's not about waiting to be convinced by the government to serve. If you're a properly raised and educated human being and American, you already know you have certain obligations and responsibilities towards your fellow-man, especially your fellow Americans. The economy is a vital element of our national infrastructure, without it we don't have a nation, and capitalists are the primary job creators in a market economy, not the government (as in Marxism).
There are incentives for capitalists in a National Socialist-run US government and country. Your business is considered a service to the country and community, providing goods and services, jobs..etc. So tax incentives, grants, contracts. Take care of your workers, make sure they're well paid and working in a safe environment, and the government will reward you. The community that your business serves will also reward you with a customer base able to afford your goods and services. The working class will have affordable housing, education, healthcare..etc. They'll live in a country with a robust, modern infrastructure, able to provide them with services, like public transit, utilities..etc.
The private sector will work in tandem with the public sector, serving the nation (the volk, the people). That is a healthy capitalism, that enriches everyone, not just the capitalist class. Working class people will also benefit from that form of capitalism. The government can also assist workers who want to organize worker-owned companies, running them as cooperatives, increasing democracy in the workplace. That's also doable in a national socialist-run economy. Laws can be passed that ensure workers own a certain % of privately owned companies. Especially large corporations, perhaps not so much smaller, mom-pop Pizzerias, but the big companies. Workers will have a seat in the boardroom.
Essentially, capitalism must be patriotic, prioritizing the needs of the people, or public good, rather than private profits.