What do you call something that makes you feel good/better, because it is good news or funny. But you were feeling normal before, you weren't sad or anything. But just by seeing that thing you felt better.
Perhaps encouraging would be serviceable,
encouraging adjective: giving hope or promise <encouraging news>
You can receive a lift from some pleasant event. Or be lifted by it.
raise (a person's spirits or confidence). "we heard inspiring talks which lifted our spirits"
synonyms: boost, raise, buoy up, elevate, give a lift to, cheer up, perk up, enliven, uplift, brighten up, lighten, ginger up, gladden, encourage, stimulate, arouse, revive, restore; More
a feeling of confidence or cheerfulness. "winning this match has given everyone a lift"
synonyms: boost, fillip, pick-me-up, stimulus, impetus, encouragement, spur, reassurance, aid, help, push;
An encouraging act or comment.
encouragement, improvement, or help: a boost to morale.
Sammy got a real boost in his confidence when he won his first ever race.
The little restaurant got a real boost when it received an excellent review in the local newspaper.
(The Free Dictionry)
Your respondents are creating a fine Thesaurus for you. I add "exhilarating".
A tonic (noun):
- (Defn. 2) anything invigorating, physically, mentally or morally
'His cheerful greeting was a real tonic.'
- (Defn. 2) something that makes you happier or healthier
'This holiday has been the perfect tonic for you.'