This app is really easy to use and has nice motivations. Its small sets that gradually increase BUT it lets you go at your own pace. You dont have to do it every other day but it will remind you if you havent done it that week. Ive been using it for a month now and enjoy it so much!
Must Have Good Appa about PushUps for Beginners - 0 to 100+ Pushups Training, v1.4