Troolz

The correct answer is either Erik Neilsen (Leslie Neilsen's brother!) or Stanley Knowles.

"Dave." Jeez, do you even parliament?

Have you tried acidophilus pills?

It isn't "just" yogurt bacilli, it's found naturally in your gut. You can find it in the vitamin section of your local Walmart or drug store.

Science is finding more and more evidence that gut bacteria have a tremendous influence on many aspects of our lives, and that we have been potentially negatively altering the composition of our gut bacteria with antibiotics and some modern foods.

Take a look at this search of Reddit for "gut bacteria" and the wide variety of topics that come up.

See also this recent AMA and this AMA by professors talking about the microbiome of our guts.

See here for a description, and plenty of warnings. The warnings are pretty amusing considering it's found naturally in your intestines in much greater quantities than you'll ingest in pill form. The pills are just an assist.

One further word of advice: some manufacturers make better pills than others. Try a couple of different reputable brands to see if one is any better than the other.

It won't cost much, try it out.

In order of payback:

Logan already answered the biggie: air sealing. Can't have enough. Go nuts in the attic: hatch (build a new one if you have to, wood and sheet foam insulation is cheap), chimney penetrations (use fireproof caulk), everywhere. Upgrading door weather stripping - buy the expensive stuff, or perhaps replace the entire door (pricier of course, but old wood doors leak both air and heat). You can pull interior casing off windows; if there's fiberglass insulation stuffed in the gap (compressed fiberglass is no longer insulation, and fiberglass is never air-tight), pull it out and use spray foam for windows. This foam is low-expansion so it doesn't blow your window frame out. If you have a sump pit, cover it off tightly so air can't enter it.

Blow insulation into the attic to a depth of R-60. Don't mix types, however - stick with the type of insulation currently in the attic (fiberglass or cellulose). Cheap and very good. Pay attention to the outer edges where the roof crosses the exterior wall plates. Make sure the attic has enough ventilation, but don't over-ventilate.

Edit: Forgot water efficiency. Replace all high-flow shower heads. Consult MaP for a new low-flow toilet.

Edit: You can try a reflective energy barrier in your attic. I don't have any experience with them, but I suspect their benefits are grossly over-sold. If I was doing new construction, I would consider ThermoStat OSB sheathing on the roof.

Use heat-reflective blinds on sunny windows in the summer, heat-retentive blinds on all windows in the winter AFTER the sun sets.

Insulate basement walls (as long as they currently stay reasonably dry year-round) with sheet foam & drywall. Pay special attention to the rim joist for air sealing and insulating - significant heat loss area. The rim joist is an area ripe for pricier DIY spray-foam if you can handle the mess it'll create.

Upgrade furnace to high efficiency (96%).

Upgrade water heater to high efficiency or on-demand.

Edit: Forgot about potential to install a Drain Waste Heat Recovery pipe. Payback-wise, probably before replacing the water heater.

Insulate the basement floor (again, as long as it has always stayed dry).

Forget about upgrading windows, there isn't a payback.

Old furnaces and inefficient water heaters aren't just energy-transfer inefficient, they also depressurize the house and create a chimney effect inside the house, sucking warm air out of the house.