Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
App Overview
Lasta Fit: Your Wellness Coach
Lasta Fit is Your Wellness Coach for Lasting Results!
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.6
2,171 ratings · Top 15%
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included18 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Differentiate and validate
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Lasta Fit: Your Wellness Coach: map the core Health & Fitness workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Allow users to customize their plans or create their own.
Assumption to check: Users often find workout plans too generic.
Validate with people who use this workflow before building.
Hypothesis 2
Introduce social features such as challenges or leaderboards.
Assumption to check: Lack of community features for motivation.
Validate with people who use this workflow before building.
Hypothesis 3
Enhance the nutrition log with barcode scanning and more detailed macro tracking.
Assumption to check: Inadequate tracking for nutrition.
Validate with people who use this workflow before building.
Hypothesis 4
Implement a guided onboarding process to simplify app usage.
Assumption to check: Confusing navigation for some users.
Validate with people who use this workflow before building.
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
App Store description
Lasta Fit is Your Wellness Coach for Lasting Results! Lasta Fit is designed to help you achieve your weight loss and wellness goals by providing an all-in-one solution for daily workouts, tracking progress, and staying motivated. Build strength, boost energy, and stay consistent — no gym required. Lasta Fit is for everyone who wants to live a more fulfilled life. Lasta Fit makes healthy living simple with gentle, low-impact movement, habit-based routines, and a practical nutrition approach designed for lasting results. Our mission is to make health and balance part of everyday life for everyone, regardless of age, weight, or background. Our programs are designed by certified fitness experts to help you move better, feel stronger, and reach your goals, whether you have 5 minutes or 30. Why users love Lasta Fit: - Personalized workout plans for all fitness levels - Track your progress and stay motivated - Daily low-impact workouts with easy-to-follow video & voice guidance - Minimal equipment needed — just bodyweight exercises - Focused programs: Weight loss, full-body workouts, abs, arms, glutes, and more Lasta Fit 28-day Personalized Programs: - Indoor Walking - Tai Chi - Tai Chi Indoor Walking - Asian Pilates - Calisthenics - Wall Pilates - Chair Yoga - Somatic Yoga - Hope Pilates - Tabata - Military Workouts - Military Calisthenics Train anytime, anywhere, and make fitness a lasting part of your life. Get a Lasta Fit PREMIUM SUBSCRIPTION and enjoy full access to all features and content. If you choose a Lasta Fit PREMIUM subscription in the app, payment will be charged to iTunes Account at confirmation of purchase. Subscription automatically renews unless auto-renew is turned off at least 24 hours before the end of the current period. The account will be charged for renewal within 24 hours before the end of the current period, and identify the cost of the renewal. The user may manage subscriptions in the iTunes settings. Auto-renewal may be turned off by going to the user's Account Settings after purchase. Privacy Policy: https://lasta-fit.com/en/privacy-policy Terms of Use: https://lasta-fit.com/en/terms-of-service Contact our customer support team at [email protected] for any assistance.
Written user reviews are not shown here. Check current App Store reviews >
Screenshots
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Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
SUGGESTED BUILD STACK
React Native
Expo
FastAPI
@react-navigation/native
chart.js
@react-native-community/async-storage
BUILD KIT DIFFICULTY
Intermediate
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.
