If you smoke, stop now. Literally cold turkey: it will save huge amounts of time and money.
Do things that bring you joy, be they gardening / crafting / sport / whatever, and make sure you make time for them: have a built-in timetable for happiness.
Find a thing you like that raises your heart level at least four times a week - could be dancing, or walking, or running, or swimming, or canoeing or whatever.
Stretch every day.
Practise saying 'no' with a smile and mean it wholeheartedly.
Buy some very sharp knives and learn how to keep them sharp.
Go to the dentist regularly.
Buy expensive shoes / boots and take them to the cobbler regularly (see also: buy a good winter coat and look after it).
Learn another language.
Make friends with older / younger people and maintain those friendships.
Use 50+ sunblock.
Always have at least one formal outfit in your wardrobe for funerals.
Moisturise your neck.
Set up internet banking with multiple accounts and sort out your savings at the start of the month, not the end.
Stay away from debt.
Get at least one cat.
Stop buying £5 wine, but don't spend £15+ on a bottle - the £8-12 price range is the best.
Kind, funny men / women are the best.
You don't have to get married or have children if you don't want to.
If you don't already have them, develop good table manners.
Learn to listen.