Not worried.
Just skimmed the above comments, and wanted to add my own opinions. Simplistically, the US federal government is the sovereign issuer of dollars (and allows banks to also create dollars through loans). Now our system for historical and practical reasons is set up so that in most cases, the federal government issues bonds or other similar instruments to provide itself with some of the dollars that it uses to pay its employees, contractors, buy supplies, etc. But it doesn't NEED to do this, the federal government could (and sometimes does) create money and then spend (this doesn't apply to states or municipalities btw).
There are some benefits to the system as it exists now, in that you create a demand for dollars which helps the country out economically, and also I think of it as a way to recycle dollars, in other words to induce those with dollars to put them to use rather than hoard. But technically, the government could stop collecting any taxes, stop issuing any bonds, and could fund all operations through dollar creation. This MIGHT result in inflation if the influx of dollars ends up competing for otherwise constrained resources, so that there are more buyers (the government is a buyer here) than sellers, so prices increase. Alternatively, it might have NO EFFECT on inflation, such as after a recession when there are idle workers/factories/etc. and the newly created dollars are not necessarily competing with the private sector.
Basically, there is a totality of economic activity that we need and demand, and the government basically wedges itself into what is mostly a public buy non-government market and appropriates, on our behalf and at our direction hopefully, a portion of that economic totality in order to provide the services and products that either can't or shouldn't be provided on the open market. So to me, the real question is not what is the size of the government, or what is the deficit or "national debt" (which are merely accounting ledgers, and not real things in and of themselves). The real question is whether the results of government activity are 1) providing us with what we are demanding through our elective government, and 2) whether this government activity is also productive in laying the groundwork for future economic growth and prosperity. In other words, it's not how much the federal government spends, but what it uses that money for that is the real issue.