If you live out in the country, it's likely that you did some tree trimming last fall, and some of the twigs, limbs, bark and branches are still aground around the yard.
We did some serious cutting last fall, knocking down a trio of chestnut trees that had died the year earlier, and, luckily, the larger pieces were sufficinetly dried-out that we were able to use lots of it for heating this winter in the trusty wood-burning stoves.
In the fall, I had piled up all the loose branches with small twigs still attached and have gone about breaking them down over the course of the winter for use as kindling. Now, since we haven't had significant snowfall or snow on the ground for the past three weeks, I am gathering all the branches up and cutting them into burnable bundles.
Going around the yard, I picked up everything from 1/4-inch diameter (kindling) to logs and branches as much as four to six inches across, pulled out the chain saw and went to work... for about an hour.
Before long, I had enough good wood to last probably ten days to two weeks, since the heating requirements going forward are not that daunting. Temperatures in this part of the world (upstate NY) run generally between lows in the 25-35-degree range and highs in the 45-60-degree range from now through the latter part of April.
At this very moment, I'm heating with some cut-up branches that were - less than an hour ago - cluttering up the ground. My indoor temperature is a pleasant 68 degrees.
Sure, some of the wood will be a little moist, so you may have to pick and choose what to burn, but bring some inside to dry out and you'll not only have gotten a little exercise, but cleaned up your yard and saved a little money on your wood heat bill.
Worst case scenario is that you'll have some intermediate-sized branches that can sit for nine months, dry out and age, and will be available when the chill comes next fall.