Is there a good iOS app for building self-discipline with customizable daily challenges?

75 Days Challenge Tough & Soft is designed for individuals seeking a structured method to build self-discipline and consistent habits. It distinguishes itself by offering two distinct modes: a rigorous 'Tough' version adhering to the strict original 75 Hard program rules, and a more adaptable 'Soft' variant. This flexibility is a core strength, catering to users who need a disciplined framework but also require the ability to adjust rules for sustainability, such as modifying diet or exercise requirements based on personal circumstances. Key features include the ability to create a fully personalized daily checklist, detailed progress tracking with streak counters, and a highly praised home screen widget that serves as a constant, glanceable reminder of daily tasks. Reviews indicate the app excels in helping users establish a routine without fostering an obsessive mindset, making it suitable for long-term lifestyle changes rather than short-term, unsustainable bursts. A minor imperfection noted by some is that task logging is entirely manual, requiring consistent daily user input. However, this manual aspect is also seen as part of the accountability process. The app does not include built-in integrations with fitness trackers or calorie counters, so data from other services must be entered manually.