For me two things really come to mind:
1. YNAB (you need a budget)
2. Yoga
During my 20's & early 30's i had always had a well paid job but nothing to show for it. I also had big overdraft which I'd never done anything about. About 6 years ago I picked up a copy of YNAB 4 for about £8 of Steam. Within 3 months I'd completely changed my spending habits.
Roll on a year or two and I'd paid off all my debts. And this program has allowed me to save for some big life events and trips - things I'd have probably borrowed money for in the past. Last year I bought my first car in full without the aid of a loan. The program also helped me when I went self empoyed a few years ago. Both mine and my long term partners finances go thought the program and we know exactly how little money we can live on - this is valuable info if times get hard. The program is basically a spreadsheet with a nice GUI but the methodology behind it work for me. If I'd have found something like this in my early 20's I'd be a lot better of than I am now. But hey, better late than never.
I do Yoga every day. Prior to me getting into Yoga I thought the only real way to exercise was to join a gym. I live in a rural part of the UK, so for me travelling to the gym is timeconsuming.
A few years back I'd been suffering back pain due to long stints sitting at a desk all day. I'd also started to put on weight due to inactivity.
Anyway, during one painful day I decided to Google "Yoga for back pain". I tried it and I was hooked. Not only did it fix my back pain, it eased it for around 3 days. Since then I've really got into Yoga and try to do at least 20-60 mins a day. Sometimes I might do it twice a day if I know I'm going to be sat down a lot.
Like everyone else I have days when I'm worn out - for these days I have a couple of 10 min routines which I try to do. I'm a firm believer of trying to exercise every day, even if it's just for 10 minutes. It's a good habit to have and doing it daily reinforces the habit.
Since doing regular practice I don't really get any achy joints. I also do HIT style Yoga 3 times a week which helps with body tone, strengh, and cardio. When you really get into Yoga you realise they're many different styles which can help different aspects of your health. For me, my main driving force was back pain - I've never done any exercise which fixed my back as well as certain Yoga exercises.
For me Yoga is great because it's easy and free. You only need a Yoga mat (a beach towel can suffice at the beginning) and Youtube to get started. I keep myself in reasonable shape without having to travel or pay any gym fees. I never knew exercise could be so easy and cheap. I wish I'd known this in my late 20's, when I put on a lot of weight, and was suffering with back pain and other achy bits.