Baby steps. That's all it takes. If you are not spending as much time outside as you would like but are hoping to increase the outdoor time in 2019, start with a small goal. It could be a couple times a week that you go for a walk around the block. 

The following week try to add an additional day for a jaunt around the block or add another block. If you use a step counter, set a goal of so many steps per outing and try to increase that number. It doesn't have to be by much. Just take a few more steps each time you go out.

Set a different goal for yourself on each outing. Go for a color walk and take note of how many different colors you see in nature. Yes, even in winter there is more than white. There are red rose hips and green moss. There are yellow and orange lichens on trees. 

Go for a texture walk and discover how many different textures there are in nature in your neighborhood. Look for the different textures of bark on trees, the different patterns in snow after the wind has blown it around. Look for animal tracks and make note of how many different types you see or how many different birds are around you.

Give camping or kayaking a try.

It doesn't take much to get out more. You just have to decide on a goal and just do it.