Another way to encourage healthy people to get insurance is to permit a set period of time (a couple of months, say) after a person becomes uninsured to purchase new insurance. If they choose not to become insured (through Medicaid, an employer, or the exchanges provided for under the ACA) within that period, they would lose guaranteed coverage for pre-existing conditions, community rating, and access to the ACA-created insurance exchange subsidies for five years. That would encourage people to buy insurance, but allow people who genuinely want to self-insure the opportunity to opt out. (It's also indisputably constitutional, regardless of what you think of Chief Justice Roberts's decision.)
2. Enact a "public option" in state insurance exchanges. During the debate over the ACA, the Congressional Budget Office estimated that adding a publicly run insurance plan would reduce the deficit by an additional $88 billion over ten years relative to the law as passed, by taking in insurance premiums and paying out less to private insurers through exchange subsidies. That's a significant bit of deficit reduction that won't require tax increases or cutting important services.
3. Repeal corn subsidies. Soda is the number one source of added sugar in the American diet, and sugar contributes to obesity. Drinking one extra can of soda per day can add over 50,000 empty calories per year -- over three weeks' worth of food, with no nutritional content. The sugar used in those drinks is mostly high fructose corn syrup, which, true to its name, is a corn product. We spend $4 billion a year on subsidies to corn farmers -- subsidies which keep corn syrup (not to mention other nutrient-free foods) artificially cheap. Repealing subsidies seems like a no-brainer way to reduce obesity and combat an epidemic that costs our medical system hundreds of billions of dollars each year.
4. Fix the medical malpractice system. Republicans (and a lot of doctors) claim that the medical malpractice system is a big reason for high spending, unnecessary use of medical services, and other problems in the health-care system. But the House is so busy repetitively repealing the ACA it hasn't gotten around to doing anything about it. Unfortunately, there's not a lot of reason to think tort reform will magically solve all the problems that are blamed on lawsuits. States like Texas that have enacted reforms haven't seen a significant reduction in medical spending, the rate at which people lack insurance, or health insurance premiums, or seen an increase in the number of doctors per capita. Maybe if fixing malpractice nationwide doesn't improve the medical system, Republicans will move on to more credible ideas for reducing spending.
5. Enact a carbon tax, or increase the gas tax. A tax on carbon dioxide emissions won't just help prevent climate change -- it'll improve our health. A carbon tax would encourage denser urban development, for instance by making it more expensive to drive to work and to heat large suburban homes -- and pollute the air. Denser development (and the need to find another way to commute and run errands) will encourage people to walk more. Walking is an effective form of exercise, and can help people maintain lower cholesterol, lower blood pressure, and lower body weight, all of which could reduce medical spending.