Great you have figured it out while you are still young, it took me until my early 70s, third trumpet in an amateur big band playing 3 and 4 hour dinner dances and being toast by the 3rd set.
Recalling what the old Soprano cornet player told me when I joined the Brass band in 1946 as an eight year old but did not understand at the time was "Hold her lightly and kiss her gently".
Watching Tine Helseth and other players seemingly effortless and learning to emulate them, now at approaching 82 I am playing a mix of 1st and 2nd parts in Big band playing longer, higher and with a much better sound, able to play 4, 45 minute sets without much fatigue.
I have stopped Free and Mouthpiece buzzing, I used to do a lot of each and have come to the conclusion they introduce unnecessary tension in the lips.
It is difficult to get the concept across in my experience, a lady that used to help us out at times in orchestra has given up playing because of chop problems playing with a lot of tension and pressure, when trying to explain to her what I am doing now she thought I had stumbled upon something but did not think it would help her.
Another friend, an average player buzzing his lips and mouthpiece before a rehearsal when asked why he was doing this as I felt it is counter productive I was firmly put in my place with "Better players than you buzz their lips and mouthpiece".
I see far too many players fighting themselves and the instrument and being content to remain so.
Regards, Stuart.