The 31-year-old was something of a surprise selection against St Mirren on Saturday, but scored the crucial opening goal before being replaced after just over an hour.
He is now hoping for more game time to get up to speed again after being a regular starter at the start of the campaign.
“It is just about building my fitness up through games, working hard in training and showing what I can do when I get the chance.”
He did that on Saturday just when it was needed, slotting home when a low cross deflected into his path to break the deadlock on the hour – just before being replaced by Josh Ginnelly.
Signed in January from New York City, MacKay-Steven started the first 11 competitive games of this season in a row, but has done so only once – away to Aberdeen – since then.
That is partly down to increased competition for places, following the signings of Ben Woodburn and Barrie McKay. But it also down to MacKay-Steven’s own injury niggle.
He’s not actually played a full 90 minutes for Hearts since the team’s last visit to Celtic Park – a 3-2 defeat in the Premier Sports Cup on August 15.
Since mid-September, the former Dundee United, Celtic and Aberdeen forward has been used mainly as an impact sub by head coach Robbie Neilson.
“I haven’t been training fully, with having a few knocks,” explained Mackay-Steven. “It was important to get some minutes [against St Mirren] and I was probably done at 60 minutes.
“But building up, we’ve got a lot of games and a strong squad. We need to use everyone and that will do me great going forward. We have a midweek and weekend game coming up. All the match minutes help, so I’m looking forward now.”
MacKay-Steven started and scored in the opening-day Premiership victory over Celtic at Tynecastle Park in July and hopes he’s done enough to be in contention to face his former club again in the reverse fixture on Thursday.
But with Liam Boyce now back from injury, competition for places at the top end of the pitch is fierce.
MacKay-Steven is essentially competing with Woodburn, McKay and Ginnelly for the two supporting forward positions Neilson prefers in his 3-4-3 formation, with Armand Armand Gnanduillet a back-up for Boyce as the advanced striker. A fully-fit Jamie Walker didn’t even make the bench on Saturday and appears to have fallen well down the pecking order.
MacKay-Steven added: “When we have a fully-fit squad, giving the manager a head ache is great. Training is competitive. We know that no matter who comes in, they can do a job and do it well.
“Every player wants to play and I’m no different. Hopefully I can keep it going and get the minutes under the belt and get the fitness and match sharpness up, which comes through games. It won’t take me long.”