Take care of your neighbors’ gardens in the spring if they have them. Volunteer to weed the garden, plant flowers, water the plants, or mulch the garden. People begin tending to their gardens as early as March so start advertising your services at the end of February or the beginning of March. It’s a great way to get outside and learn how to garden.
However, like anything else truly worthwhile, apps require a significant investment of your time or money upfront. If you don't have the skills, then you have to hire someone who can assist you in creating a great app. But first you need to come up with an idea that will sell. Do the proper market research and analytics to come up with the right app.