Hi, the question you ask is often asked by many of us, to ourselves...
If you're not getting paid to ride the bike, then it really falls to you to decide to balance what you like with what might give other benefits - like health and fitness.
You don;t mention how often and for how long you ride... an important consideration.
Riding is a 'Balance' thing, beyond just balancing on the bike.
Cycling requires both 'power' and 'endurance' - the balance point of these may be where you wish to go and be.
The smaller gears seem to tire you more than riding a harder gear - that may be because your cardio fitness is limiting you...
A smaller gear pedaled faster uses more cardio fitness, faster. A larger gear exerts the muscle power faster/greater.
There is a balance area between using both which allows both power and longer, better endurance.
That's an area worth finding - your husband is obviously trying to point you there.
An interesting thing is that riding a large gear at slow pedal rates (pedal rate called 'cadence') doesn't often build more muscle or strength. It depends...
Often a slow cadence rider hits a ceiling, through which they aren't able to go faster...
Not knowing what your husband advises (the particulars) it's hard to say more, but pedaling a slightly smaller gear at a faster 'cadence', over time/days/months, will help to improve your overall fitness, a possible improvement in general health.
Muscle mass isn;t everything, it certainly can be an aid, but there are many very strong riders who might be considered to have 'chicken legs'.
Discuss the particulars of changing, adapting your cycling to a smaller gear-faster cadence with your husband. Give it a try for an extended period. You may find it works for you.
In improved riding, improved health, more joy and fun.
Ride On
Yuri - time riding a bike is not subtracted from your years of life...