Joined at 25, loads of lads younger than me, few my age, few older.
No issues, quite humbling as they are all incredibly fit.
Train 3 days a week (Mon-Wed-Fri). Optional circuit on Sunday sometimes.
Spar once a week w/ headgear and built up to it over 2-3 months. Sparring is controlled but it's adrenaline.jpg.
Trainer said weight training can be used to supplement the boxing on off days but not advised as you need explosive power and not necessarily strength.
I've maintained if not added muscle mass through boxing and minimal lifting. Lots of push ups, running, box jumps, etc all help. Shoulders are biggest improvement with regards to muscular development.
It's a fun, challenging, and technical skill that will undoubtedly improve your fitness levels.