This post
here gives a lot of different ways to get your sims into any/all moods.
There are two main ways sims become (for example) inspired.
1. by the surrounding environment. Which is fine as long as they stay in that room.
2. by changing their emotions through doing something like cloud gazing or drinking a certain mixology drink. The sim will stay in this mood more-or-less wherever they go for as long as the moodlet is present. Somewhere between 4-6 hours. The only thing that would cancel out this kind of mood would be a stronger environment score or if they experience a stronger emotion such as 'very sad' or 'very embarrassed'
If your sim is at home cooking, as long as the kitchen has an overall inspired aura then your sim will besome inspired. But when your sim leaves that room or the house then if you have not made them 'do' anything to get a certain mood/emotion then they will default to 'fine' of maybe 'happy'.
Before my sims leave for work I stack up a lot of actions so that they have at least 16+ of whatever mood they need. That way they can work hard for as long as the moodlets last. There are some now that will last the entire work shift. This works much better than just having one inspired moodlet. It takes about an hour to do it all so when I get the 'work shift starts in one hour' notice I start my sim doing all the things to get him inspired.
For example, cloud gaze, drink Pros and Prop, Reminisce on Inspired memory, Eat perfect grape, view inspired art, etc
Even certain conversations really help such as getting another sim to tell your worker sim a 'deep secret'. This gives a nice moodlet that will help to stack up the inspired one.
Upgraded showers/basins also help to stack up good moodlets.
Eating fruit/vegies etc from your garden are a good way to boost the target emotion too.
If you find your sims don't have enough time to do anything extra there are time saving 'tricks' to help. One trick for saving time is to get the most expensive bed as soon as possible as the sims energy bar will refill much faster; just like the most expensive shower upgraded will make your sims shower a lot quicker too.